References to mostly single crystal spectra with some diffuse reflection data, and articles about the color in some minerals.

Books

• Platonov AN (1976) The nature of colour in minerals. Kiev, Naukova Dumka (in Russian).
• Platonov AN (1976) Typomorphic value of the color of minerals. Abakumova NB editor. Fiz. Miner. Probl. Tipomorfizma, Mater. Vses. Konf. (1976), 31-9 (In Russian).
• Platonov AN, Taran MN, Balitsky V (1984) природа окраски самоцветов (The nature of the color of gems) 197 pages. Moscow, Nedra (in Russian)
• Platonov AN,  Khomenko VM, Tarashchan A (2013) Оптическая спектроскопия и люминесценция породообразующих слюд и хлоритов [Optical spectroscopy and luminescence of rock-forming micas and chlorites]
• Platonov AN, Tarran, MN (1977) Some problems of the optical spectroscopy of gem stones. Lazarenko EK ed. Vopr. Reg. Genet. Mineral., [S'ezde Ukr. Mineral. O-va.], 2nd (1977), 11-21(In Russian).
• Matsuk SS, Platonov AN,  Khomenko VM (1985) Оптиуеские Спектры и Окраска Мантийных Минералов В Кимберлитах. [Optical Spectra and Coloring of Mantle Minerals in Kimberlites]

Optical Spectra of Afghanite, (Na,K)₂₂Ca₁₀[Si₂₄Al₂₄O₉₆](SO₄)₆Cl₆  

• Ziya-Zada, A. K.; Platonov AN, Tarashchan AN, Belichenko VP (1971) Spectroscopic properties of afghanite. Mineralogicheskii Sbornik (Lvov) 25, 352-354. (In Russian)
• Krzemnicki MS, Rochd C (2024) Afganite of Exceptional Size and Quality from Badakhshan, Afghanistan. The Journal of Gemmology 39, 7-8.
  

Optical Spectra of Akaganeite FeO(OH)

• Taylor LA, Mao HK, Bell PM (1974) Identification of the hydrated iron oxide mineral akaganeite in sample 66095,85. Carnegie Inst Washington Yearbook 73:477-480.

Optical Spectra of Akermanite, Ca₂MgSi₂O₇

• Sugimoto A, Nobe Y, Yamazaki T, Anzai Y, Yamagishi K, Segawa Y, Takei H (1997) Spectroscopic properties of Cr-doped melilite crystals. Physics and Chemistry of Minerals 24, 326-332.

Optical Spectra of Alleghanyite, Mn₅(SiO₄)₂(OH)₂  

• Lakshmi RS, Padma SK, Udayabhaska RG, Endo T, Frost RL (2014) Spectroscopic characterization of manganese minerals. Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 117, 270-5.  

Optical Spectra of Alunite, KAl₃(SO₄)₂(OH)₆ 

• Vedanand S, Rao PS, Reddy YP, Nagarajan T, Reddy BJ (1992) Moessbauer, optical, and EPR spectral studies of alunite. Physica Scripta 45, 414-16.

Optical Spectra of Amesite, Mg₂Al(AlSiO₅)(OH)₄

• Platonov AN, Langer K, Wieviora A, Andrut M (1995) Electronic absorption spectra of chromium-bearing amesite. European Journal of Mineralogy 7, 961-965.

Optical Spectra of Anabergite, Ni₃(AsO₄)₂·8H₂O

• Faye GH (1971) A Semi-quantitative Microscope Technique for Measuring the Optical Absorption Spectra of Mineral and Other Powders. The Canadian Mineralogist 10, 889-895.

Optical Spectra of Anapaite, Ca₂Fe(PO₄)₂·4H₂O

• Platonov AN, Polshin EV, Tarashchan AV, Vorobev IB (1972) Moessbauer and optical spectroscopy of iron in some natural phosphates. Mineralogicheskii Sbornik (Lvov) 26, 257-68. (In Russian)

Optical Spectra of Anatase, TiO₂

• Hosaka N, Sekiya T, Satoko C, Kurita S (1997) Optical properties of single-crystal anatase TiO₂. Journal of the physical Society of Japan 66, 877-880.
• Sekiya T, Ichimura K, Igarashi M, Kurita S (2000) Absorption spectra of anatase TiO₂ single crystals heat-treated under oxygen atmosphere. Journal of Physics and Chemistry of Solids 61, 1237-1242. 

Optical Spectra of Andersonite, Na₂Ca(UO₂)(CO₃)₃·5-6(H₂O)

• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of Antigorite, Mg₃(Si₂O₅)(OH)₄

• Reddy SN, Ravikumar RVSSN, Reddy BJ, Reddy YP, Rao PS, (2001) Spectroscopic investigations on Fe³⁺, Fe²⁺ and Mn²⁺ bearing antigorite mineral. Neues Jahrbuch fuer Mineralogie, Monatshefte (2001), 261-270. 

Optical Spectra of Antlerite, Cu₃(SO₄)(OH)₄

• Reddy RRS, Lakshmi RS, Siva RG, Reddy BJ (2002) Spectral studies of divalent copper in antlerite mineral. EPR in the 21st Century: Basics and Applications to Material, Life and Earth Sciences, Proceedings of the Asia Pacific EPR/ESR Symposium, 3rd, Kobe, Japan, Oct. 29-Nov. 1, 2001 (2002), 589-594.
• Reddy RRS, Reddy SL, Reddy GS, Reddy BJ (2002) Crystal Research and Technology 37, 485-490.   

Optical Spectra of Apjohnite, MnAl₂(SO₄)₄·22H₂O₄

• Reddy SL, Reddy GS, Wain DL, Martens WN, Reddy BJ, Frost RL (2006) Electron paramagnetic resonance, optical absorption and IR spectroscopic studies of the sulphate mineral apjohnite.Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 65, 1227-1233   

Optical Spectra of Ardennite-(As), Mn₄Al₄(AlMg)(AsO₄)(SiO₄)₂(Si₃O₁₀)(OH)₆

• Chandrasekhar AV, Venkataramanaiah M, Reddy BJ (1996) Mn²⁺ and Fe³⁺ impurities in ardennite by spectroscopic investigations. Indian Journal of Pure and Applied Physics 34, 193-196.  
• Lakshmi RS, Padma SK, Udayabhaska RG, Endo T, Frost RL (2014) Spectroscopic characterization of manganese minerals. Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 117, 270-5.  

Optical Spectra of Astrophyllite, K₂NaFe₇Ti₂Si₈O₂₆(OH)₄F

• Manning PG (1969) On the origin of colour and pleochroism of astrophyllite and brown clintonite. Canadian Mineralogist 9, 663.677.

Optical Spectra of Aurichalcite, (Zn,Cu)₅(CO₃)₂(OH)₆ 

• Vedanand S, Sudhana BM, Reddy BJ, Rao PS (1996) EPMA, EPR, electronic and vibrational spectral studies on natural aurichalcite. Bulletin of Materials Science 19, 1089-1094.
• Reddy BJ, Nieto F, Navas AS (2004) Spectroscopic characterisation of rosasite and aurichalcite. Neues Jahrbuch fur Mineralogie-Monatshefte 2004, 302-316. 
• Klokishner S, Behrens M, Reu O, Tzolova-Muller G, Girgsdies F, Trunschke A, Schlogl R (2011) Cation Ordering in Natural and Synthetic (Cu_1-​xZn_x)​₂CO₃(OH) ​₂ and (Cu_1-​xZn_x) ​₅(CO₃)​₂(OH) ​₆. Journal of Physical Chemistry A, 115, 9954-9968.   

Optical Spectra of Azurite, Cu₃(CO₃)₂(OH)₂ 

• Reddy BJ, Sarma, KBN (1981) Absorption spectra of copper(2+) in azurite. Solid State Communications 38, 547-9.
• Sarma KBN, Reddy BJ, Lakshman SVJ (1984) EPR and optical spectra of certain copper-​bearing minerals:  a tool to probe site symmetry of copper(II) ion. Proceedings of the Nuclear Physics and Solid State Physics Symposium (1984),  25, 209-10.  
• Peng SS, Chen TH, Chen JJ (2008) Investigation on the local structure, optical absorption spectra of malachite and azurite. Guisuanyan Tongbao 27, 1040-1043, 1047. (In Chinese) 

Optical Spectra of Bazzite, Be₃Sc₂(Si₆O₁₈) 

• Platonov AN, Polshin ZV, Tsistlyakova MV, Taran MN (1981) ОБ изоморфные железа в Бацци из пегматитов казахстана (About isomorphism of iron in bazzites from pegmatitres of Kazakhstan). Geochemistry 3, 393-398.
  
• Taran MN, Dyar MD, Khomenko VM, Boesenberg JS (2017) Optical absorption, Mössbauer, and FTIR spectroscopic studies of two blue bazzites. Physics and Chemistry of Minerals 44, 497-507.

Optical Spectra of Beaverite,  PbCu²⁺(Fe³⁺,Al)₂(SO₄)₂(OH)₆

• Fayazyddin M, Reddy NCG, Reddy GS, Reddy SL, Rao PS, Frost RL (2007) Optical absorption and EPR studies on beaverite mineral. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 68, 807-810. 

Optical Spectra of "Bentonite"

• Hradil D, Grygar T, Hrušková M, Bezdicka P, Lang K, Schneeweiss O, Chvátal M (2004) Green Earth Pigment from the Kadan Region, Czech Republic: :Use of Rare Fe-rich Smectite. Clays and Clay Minerals 52, 767–778.

Optical spectra of Bergenite, Ca₂Ba₄(UO₂)₉O₆(PO₄)₆·16H₂O

• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of Bernalite, Fe(OH)₃·nH₂O

• McCammon CA, Pring A, Keppler H, Sharp T (1995) A study of bernalite, Fe(OH)₃, using Mössbauer spectroscopy, optical spectroscopy and transmission electron microscopy. Physics and Chemistry of Minerals 22, 1–20.
  

Optical Spectra of Boracite, Mg₃B₇O₁₃Cl

• Pisarev RV, Druzhinin  VV, Prochorova SD, Nesterova NN, Andreeva GT (1969) Crystal Field Theory and Optical Absorption of Cobalt and Nickel Boracites. phys stat sol 35, 145-155.

Optical Spectra of Bornite, Cu₅FeS₄ 

• Ramanaiah MV, Ravikumar RVSSN, Srinivasulu G, Reddy BJ, Rao PS (1996) Detailed spectroscopic studies on cornetite from southern Shaba Zaire. Ferroelectrics 175, 175-182. 
• Ramanaiah MV, Ravikumar RVSSN, Chandrasekhar AV, Reddy BJ, Reddy YP, Rao PS (1998) Tetrahedral site of Cu(II) in bornite and bournonite. Ferroelectrics 216, 27-34.  

Optical Spectra of Bournonite, PbCuSbS₃ 

• Ramanaiah MV, Ravikumar RVSSN, Chandrasekhar AV, Reddy BJ, Reddy YP, Rao PS (1998) Tetrahedral site of Cu(II) in bornite and bournonite. Ferroelectrics 216, 27-34.  

Optical Spectra of Brackebuschite, Pb₂Mn(VO₄)₂(OH) 

• Platonov AN. Tarashchan AN. Povarennykh AS. Zakharova GM (1971) Optical spectroscopy of vanadium in natural minerals.  I.  Optical absorption spectra of natural orthovanadates. Konstitutsiya i Svoistva Mineralov 5, 92-100. (In Russian).

Optical Spectra of Bridgmanite, (Mg,Fe)SiO₃ 

• Keppler H, McCammon CA, Rubie DC (1994) Crystal-field and charge-transfer spectra of (Mg,Fe)SiO₃ perovskite. American Mineralogist 79, 1215–1218.
• Keppler H , Dubrovinsky LS, Narygina O, Kantor I, (2008) Optical Absorption and Radiative Thermal Conductivity of Silicate Perovskite to 125 Gigapascals. Science 322, 1529-1532.   

Optical Spectra of Brochantite, Cu₄(SO₄)(OH)₆ 

• Reddy KM, Jacob AS, Reddy BJ, Reddy YP (1987) Optical absorption spectra of copper(2+) in brochantite. Physica Status Solidi B:  Basic Research 139, K145-K150.  

Optical Spectra of Brownmillerite, Ca₂(Al,Fe)₂O₅ 

• Jiang P, Li J, Ozarowski A, Sleight AW, Subramanian MA (2013) Intense Turquoise and Green Colors in Brownmillerite-Type Oxides Based on Mn⁵⁺ in Ba₂In_2−xMnxO_5+x. Inorganic Chemistry 52, 1349-1357.

Optical Spectra of Bustamite, CaMn(Si₂O₆) 

• Manning PG (1968b) Absorption spectra of the manganese-bearing chain silicates pyroxmanganite, rhodonite, bustamite and serandite. Canadian Mineralogist 9, 348-357
• Manning PG (1970) Racah parameters and the relationship to lengths and covalence of Mn²⁺- and Fe³⁺-oxygen bonds in silicates. Canadian Mineralogist 10, 677-688.

Optical Spectra of Cancrinite, (Na,Ca,◻)₈(Al₆Si₆O₂₄)(CO₃,SO₄)₂·2H₂O 

• Platonov AN, Belichenko VP (1965) Nature of color of cancrinites from the Azov area. Mineralogicheskii Sbornik (Lvov) 19, 153-63. (In Russian)
• Novozhilov AI, Samoilovich MI, Mikulskaya EK, Parushnikova LI (1966) Nature of the blue coloration of cancrinite crystals. Zap Vses Mineral Ova 95, 736-738 (In Russian)

Optical Spectra of Carnotite, K₂(UO₂)₂(VO₄)₂·3H₂O 

• Platonov AN, Tarashchan AN, Povarennykh AS (1972) Optical spectroscopy of vanadium in natural minerals.  II.  Optical absorption spectra of vanadates with complex radicals. Konstitutsiya i Svoistva Mineralov 6, 58-62. (In Russian) 

Optical Spectra of Carpholite, MnAl₂(Si₂O₆)(OH)₄

• Weiser F, Abs-Wurmbach I, Seidel E (1996) Crystal-chemical relations of iron in natural Mg-carpholites: a spectroscopic study. Physics and Chemistry of Minerals 23, 237-246.

Optical Spectra of Cassiterite, SnO₂ 

• Calas G, Cottrant JF (1982) Cristallochime du fer dans les cassitérites bretonnes. Bull Minéral 105, 598-605. 
• Cohen AJ, Adekeye JID, Hapke B, Partlow D (1985) Intersitial Sn²⁺ in synthetic and natural cassiterite crystals. Physics and Chemistry of Minerals 12:, 363-369.
• Peng M, Zheng C, Lu W, Zou Z (1985) [A spectroscopic study of cassiterites from four types of tin deposits in China.] Mineral Deposits 4, 69-76. (In Chinese)
• Huang W, Zhou J, Shui T, Pan J, Meng F, Zo R, Dong S, Cao S (2024) Gemological and Trace Element Characteristics of Cassiterite from Yunling, China. Gems & Gemology 60. 168-13.
  

Optical Spectra of Celestine, SrSO₄ 

• Friend JN, Allchin JP (1939) Colour of Celestine. Nature 1939, 633.
• Isetti G (1970)  Studio Sulla Colorazione Della Celestina. Doriana 4, 1-7. In Italian
• Bakhtin AI, Khasanov RA, Vinokurov VM (1973) Electron paramagnetic resonance and optical absorption spectra of some defect centers in barites and celestites. Vinokurov VM editor. Sostav, Strukt. Svoistva Miner. (1973), 84-90. (In Russian)
• Bernstein LR (1979) Coloring mechanismsin celestite. American Mineralogist 64, 160-168.
• Catheliueau T (2020) Celestine from Madagascar. The Journal of Gemmology 37, 344-345.

Optical Spectra of Chalcanthite, CuSO₄·5H₂O 

• Lakshman SVJ, Reddy BJ (1973) Optical absorption spectra of copper(2+) ion in chalcanthite and malachite. Canadian Mineralogist 12, 207-210.  

Optical Spectra of Chalcocite, Cu₂S

• Reddy SL, Fayazuddin M, Frost RL, Endo T (2007) Electron paramagnetic resonance and optical absorption spectral studies on chalcocite, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 68, 420-423.  

Optical Spectra of Chalcomenite, CuSeO₃·2H₂O 

• Frost RL, Reddy BJ, Keeffe EC (2008) An application of the near infrared spectroscopy to the study of the selenite minerals: chalcomenite, clinochalcomenite and cobaltomenite. Journal of Near Infrared Spectroscopy 16, 399-407.

Optical Spectra of Chalcophyllite, Cu₁₈Al₂(AsO₄)₄(SO₄)₃(OH)₂₄·36H₂O

• Frost RL, Reddy BJ, Keeffe EC (2010) Spectroscopy of selected copper group minerals: Chalcophyllite and chenevixite-implications for hydrogen bonding. Spectrochimica Acta Part A 77, 388–396.

Optical Spectra of Chalcopyrite, CuFeS₂

• Reddy GU, Seshamaheswaramma K, Nakamura Y, Reddy SL, Frost RL, Endo T (2012) Electron paramagnetic resonance, optical absorption and Raman spectral studies on a pyrite/chalcopyrite mineral. .Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 96, 310-315. 
• Todoran R, Todoran D (2012) Determination optical functions and energetic properties for chalcopyrite minerals. Proceedings of the Physics Conference (TIM-11), 2011, 198-203.  AIP Conference Proceedings (2012)
• Prameena B, Anbalagan G, Gunasekaran S, Ramkumaar GR, Gowtham B (2014) Structural, optical, electron paramagnetic, thermal and dielectric characterization of chalcopyrite. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 122, 348-355.  

Optical Spectra of Charoite, (K,Sr,Ba,Mn)_15-16(Ca,Na)₃₂[Si₇₀(O,OH)₁₈₀](OH,F)₄·nH₂O

• Buhtiarova EV, Bublikova TM (1993) Main Gemmological Characteristics of Charoite from Eastern Siberia. Abstract presented at the 24th International Gemmological Conference, 2-15 October 1993, France.

Optical Spectra of Chenevixite, Cu₂Fe₂(AsO₄)₂(OH)₄ 

• Frost RL, Reddy BJ, Keeffe EC (2010) Spectroscopy of selected copper group minerals: Chalcophyllite and chenevixite-implications for hydrogen bonding. Spectrochimica Acta Part A 77, 388–396.

Optical Spectra of Chlorites, (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6 

• White WB, Keester KL (1966) Optical absorption spectra of iron in the rock-forming silicates. American Mineralogist 51, 774-791. 
• Marfunin AS, Mkrtchyan AR, Nadzharyan GN, Nyussik YM, Platonov AN (1971) Optical and Moessbauer spectra of iron in some layered silicates. Izvestiya Akademii Nauk SSSR, Seriya Geologicheskaya 1971, 87-93. (In Russian)
• Smith G, Strens RGJ (1976) Intervalence transfer absorption in some silicate, oxide and phosphate minerals. In: Strens, RGJ, ed, The Physics of Minerals and Rocks. Wiley, New York. pp. 583-612
• Smith G (1977) Low-temperature optical studies of metal-metal charge-transfer transitions in various minerals. Canadian Mineralogist 15:500-507.
• Calas G, Manceau A, Novikoff A, Boukili H (1984) Comportement du chrome dans les minéraux d'altération du gisement de Campo Formoso (Bahia, Brásil). Bull Minéral 107, 755-766.
• Hålenius U (1984) The crystal field spectra of Mn³⁺ in chlorite. Geologiska Föreningens i Stockholm Förhandlingar 106, 51-57.
• Bakhtin AI (1986) The distribution of Fe ions in chlorites. Geokhimiya 10, 1519-1523. (In Russian).  Translation: Geochemistry International 23:63-67.
• Platonov AN, Langer K, Andrut M, Calas G (1996) Cr³⁺ in phyllosilicates: Influence of the nature of coordinating ligands and their next cationic neighbors on the crystal field parameters. Mineral Spectroscopy: A tribute to Roger G. Burns. The Geochemical Society, Special Publication No. 5. Dyar MD and Schaefer MW eds, pp 41-48.
• Chadwick KM (2008) Chromium-rich clinochlore (kämmererite) from Turkey. Gems & Gemology 44, 168-169.
• Platonov AN, Kravchenko GL (2010) Optical spectroscopic study of ferroan clorites from metasomatically alterated rocks in western Peri-Azovian area. Mneralogical journal (Ukraine) 32, 27-37 (in Russian).
• Platonov AN,  Khomenko VM, Tarashchan A (2013) Оптическая спектроскопия и люминесценция породообразующих слюд и хлоритов [Optical spectroscopy and luminescence of rock-forming micas and chlorites] Kiev, Naukova Dumka. 297 pages.

Optical Spectra of Chromite, FeCr₂O₄ 

• Mao HK, Bell PM (1974) Crystal-field effects in spinel: oxidation states of iron and chromium. Carnegie Inst. Washington Yearbook 73, 332-341. 
• Reddy BJ, Frost RL (2005) Spectroscopic characterization of chromite from the Moa-Baracoa Ophiolitic Massif, Cuba. Spectrochimica Acta A - Molecular and Biomolecular Spectroscopy 61, 1721-1728.

Optical Spectra of 'Chrysocolla', (Cu,Al)₂H₂Si₂O₅(OH)₄•nH₂O

• Lakshman SVJ, Reddy BJ, Janardhanam K, Murthy VLR, Devi PR (1978) Electronic absorption in silicate mineral of copper. Czechoslovak Journal of Physics  B28, 1122-4.  
• Ravikumar RVSSN, Madhu N, Chandrasekhar AV, Reddy BJ, Reddy YP, Rao PS (1998) Cu(II)​, Mn(II) in tetragonal site in chrysocolla. Radiation Effects and Defects in Solids 143, 263-272.   
• Ye M, Shen AH (2020) Gemmological and mineralogical characteristics of chrysocolla chalcedony from Taiwan, Indonesia and the USA, and their separation. The Journal of Gemmology 37, 262-280.

Optical Spectra of "Chrysotile", Mg₃(Si₂O₅)(OH)₄

• Faye GH (1971) A semi-quantitative microscope techique for measuring the optical absorption spectra of mineral and other powders. The Canadian Mineralogist 10, 889-895. 
• Faye GH (1974) Optical absorption spectrum of Ni²⁺ in garnierite: A discussion. Canadian Mineralogist 12, 389-393.
• Reddy BJ, Sarma KBN (1982) Electronic absorption spectrum of chrysotile asbestos. Indian Journal of Physics, B 56B, 29-34.    
• Platonov AN, Langer K. Wievióra A, Andrut M (1995) Electronic absorption spectra of chromium-bearing amesite. European Journal of Mineralogy 7, 961-965.

Optical Spectra of Chukhrovite, Ca_4.5Al₂(SO₄)F₁₃·12H₂O 

• Gorobets BS, Rogozhin AA, Ryabenko SV (1989) Determination of rare-​earth minerals under unfiltered light from a mercury lamp. Mineralogicheskii Zhurnal 11, 55-7. (In Russian)

Optical Spectra of Clinochalcomenite, CuSeO₃·2H₂O 

• Frost RL, Reddy BJ, Keeffe EC (2008) An application of the near infrared spectroscopy to the study of the selenite minerals: chalcomenite, clinochalcomenite and cobaltomenite. Journal of Near Infrared Spectroscopy 16, 399-407.

Optical Spectra of Clinochlore, Mg₅Al(AlSi₃O₁₀)(OH)₈ 

• Calas G, Manceau A, Novikoff A, Boukili H (1984) Comportement du chrome dans les minéraux d'altération du gisement de Campo Formoso (Bahia, Brásil). Bull Minéral 107, 755-766.
• Platonov AN, Langer K, Andrut M, Calas G (1996) Cr³⁺ in phyllosilicates: Influence of the nature of coordinating ligands and their next cationic neighbors on the crystal field parameters. Mineral Spectroscopy: A tribute to Roger G. Burns. The Geochemical Society, Special Publication No. 5. Dyar MD and Schaefer MW eds, pp 41-48.
• Chadwick KM (2008) Chromium-rich clinochlore (kämmererite) from Turkey. Gems & Gemology 44, 168-169.

Optical Spectra of Clinohumite, Mg₉(SiO₄)₄F₂

• Bukanov, V. V.; Platonov AN, Taran MN, Pol'shin EV (1977) Study of the color of clinohumite - a new jewelry stone. Konstitutsiya i Svoistva Mineralov 11, 36-41. (In Russian)
• Langer K, Platonov AN, Matsuk SS, Wilder M (2002) The crystal chemistry of the humite minerals: Fe²⁺-Ti⁴⁺ charge transfer and structural allocation of Ti⁴⁺ in chondrodite and clinohumite. European Journal of Mineralogy 14, 1027-1032.
• Reddy SL, Reddy NCG, Reddy GS, Reddy BJ, Frost RL (2006) Characterization of clinohumite by selected spectroscopic methods. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 65, 684-688.  

Optical Spectra of Clintonite, CaAlMg₂(SiAl₃O₁₀)(OH)₂ 

• Manning PG (1969) On the origin of colour and pleochroism of astrophyllite and brown clintonite. Canadian Mineralogist 9, 663.677.

Optical Spectra of Clinozoisite, Ca₂Al₃(Si₂O₇)(SiO₄)O(OH) 

• Reddu BK. Sarma KBN (1982) Absorption spectra of Mn²⁺  in manganoan clinozoisite. Acta Phsysica Academiae Scientiarum Hungaricae 53, 117-122.
  
• Taran MN, Platonov AN, Petrusenko S, Khomenko VM (1984) Optical absorption spectra of Mn³⁺ ion in natural clinozoisites. Geokhimiya, Mineralogiya i Petrologiya 19, 43-51 (In Russian) 
• Petrusenko S, Taran MN, Platonov AN, Gavorkyan SV (1992) Optical and infrared spectroscopic studies of epidote group minerals from the Rhodope region.Spisanie na Bulgarskoto Geologichesko Druzhestvo 53, 1-9.  In Russian    
• Langer K, Tillmanns E, Kersten M, Almen H, Arni RK (2002) The crystal chemistry of Mn3+ in the clino- and orthozoisite structure types, Ca₂M₃³⁺[OH|O|SiO₄|Si₂O₇]: A structural and spectroscopic study of some natural piemontites and “thulites” and their synthetic equivalents. Zeitschrift für Kristallographie 217, 563-580.
• Reddy SL, Maheswaramma KS, Reddy RR, Reddy AV, Nakamura y, Reddy BJ, Endo T, Frost RL (2011) Electron paramagnetic resonance, NIR studies on zoisite, clinozoisite and chrom-zoisite minerals. Spectrochimica Acta A 78, 1240-1244.

Optical Spectra of Coalingite, Mg₁₀Fe₂(OH)₂₄[CO₃]·2H₂O 

• Mattson SM, Rossman GR (1984) Ferric iron in tourmaline. Physics and Chemistry of Minerals 14, 225-234

Optical Spectra of Cobaltite, CoAsS 

• Ravikumar RVSSN, Chandrasekhar AV, Reddy BJ, Reddy YP, Rao PS (1998) Electronic spectra of cobaltite. Modern Applications of EPR/ESR: From Biophysics to Materials Science, Proceedings of the Asia-Pacific EPR/ESR Symposium, 1st, Kowloon, Hong Kong, Jan. 20-24, 1997, 523-527.

Optical Spectra of Cobaltomenite, CoSeO₃·2H₂O 

• Frost RL, Reddy BJ, Keeffe EC (2008) An application of the near infrared spectroscopy to the study of the selenite minerals: chalcomenite, clinochalcomenite and cobaltomenite. Journal of Near Infrared Spectroscopy 16, 399-407.

Optical Spectra of Condrodite, (Mg,Fe)₅(SiO₄)₂(F,OH)₂ 

• Langer K, Platonov AN, Matsyuk SS, Wildner M (2002) The crystal chemistry of the humite minerals: Fe²⁺-Ti⁴⁺ charge transfer and structural allocation of Ti⁴⁺ in chondrodite and clinohumite. European Journal of Mineralogy 14, 1027–1032. 

Optical Spectra of Conichalcite, CaCu(AsO₄)(OH) 

• Reddy BJ, Frost RL, Martens WN (2005) Characterization of conichalcite by SEM, FTIR, Raman and electronic reflectance spectroscopy. Mineralogical Magazine 69, 155-167.   

Optical Spectra of Connellite, Cu₁₉(SO₄)(OH)₃₂Cl₄·3H₂O 

• Sreeramulu P, Reddy KM, Jacob AS, Reddy BJ (1990) UV-​VIS, NIR, IR, and EPR spectra of connellite. Journal of Crystallographic and Spectroscopic Research 20, 93-96.

Optical Spectra of Cornetite, Cu₃(PO₄)(OH)₃ 

• Ramanaiah MV, Ravikumarn RVSSN, Srinivasulu G, Reddy BJ, Rao PS (1996) Detailed spectroscopic studies on cornetite from southern Shaba, Zaire. Ferroelectrics 175, 175-182.

Optical Spectra of Corvusite, (Na,Ca,K)(V⁵⁺,V⁴⁺,Fe)₈O₂₀·4H₂O

• Platonov AN, Tarashchan AN (1973) Optical spectroscopy of vanadium in natural minerals.  III.  Absorption spectra of vanadium(4+) and vanadium(3+) complexes. Konstitutsiya i Svoistva Mineralov 7, 75-81. (In Russian)
  

Optical Spectra of Covellite, CuS 

• Sowjanya G, Reddy NCG, Reddy SL, Reddy BJ, Frost RL (2008) Electron paramagnetic resonance and optical absorption spectral studies on covellite mineral . Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 71, 751-754.

Optical Spectra of Crocoite, PbCrO₄

• Grum-Grzhimailo SV (1940) The coloring of minerals caused by chromium. Trav. lab. crist., Acad. sci. U.R.S.S. (1940), 73-86.  
• Abu-Eid RM (1976) Absorption spectra of transition metal-bearing minerals at high pressures. In: The Physics and Chemistry of Minerals and Rocks. Strens RGJ, ed, J Wiley, New York, p 641-675 
• Reddy BJ, Sarma KBN (1981) Optical properties of chromate centers in crocoite. Physics Letters A, 86A, 386-388.
• Cathelineau T (2022) Crocoite from Tasmania, Australia. Journal of Gemmology 38, 9-11.

Optical Spectra of Cuprorivaite, CaCuSi₄O₁₀ 

• Accorsi G, Verri G, Bolognesi M, Armaroli N, Clementi C, Miliani C, Romani A (2009) The exceptional near-infrared luminescence properties of cuprorivaite (Egyptian blue). Chemical Communications, 2009, 3392–3394.

Optical Spectra of Delvauxite, ~CaFe₄(PO₄,SO₄)₂(OH)₈·4-6H₂O

• Platonov AN, Polshin EV, Tarashchan AV, Vorobev IB (1972) Moessbauer and optical spectroscopy of iron in some natural phosphates. Mineralogicheskii Sbornik (Lvov) 26, 257-68. (In Russian)
  

Optical Spectra of Demesmaekerite, Pb₂Cu₅(UO₂)₂(SeO₃)₆(OH)₆·2H₂O 

• Frost RL, Reddy BJ, Dickfos MJ (2008) An application of near-infrared and mid-infrared spectroscopy to the study of uranyl selenite minerals: derriksite, demesmaekerite, guilleminite and haynesite. Journal of Near Infrared Spectroscopy 16, 455-469.

Optical Spectra of Derriksite, Cu₄(UO₂)(SeO₃)₂(OH)₆ 

• Frost RL, Reddy BJ, Dickfos MJ (2008) An application of near-infrared and mid-infrared spectroscopy to the study of uranyl selenite minerals: derriksite, demesmaekerite, guilleminite and haynesite. Journal of Near Infrared Spectroscopy 16, 455-469.

Optical Spectra of Descloizite, PbZn(VO₄)(OH)  

• Platonov AN, Tarashchan AN, Povarennykh AS, Zakharova GM (1971) Optical spectroscopy of vanadium in natural minerals. I. Optical absorption spectra of natural orthovanadates. Konstitutsiya i Svoistva Mineralov 5, 92-100. (In Russian)
• Reddy SL, Reddy BJ, Frost RL (2009) Spectroscopic investigations of descloizite. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 72, 194-197.

Optical Spectra of Dioptase, CuSiO₃·H₂O 

• Reddy KM, Jacob AS, Reddy BJ (1986) EPR and optical spectra of copper(2+) in dioptase. Ferroelectrics, Letters Section 6, 103-112. 
• Huang YP, Meng J, Wang LJ, Feng WL (2008) Theoretical investigation of the optical spectra and g factors for Cu²⁺ in dioptase. Philosophical Magazine, 88, 1701-1704.   

Optical Spectra of Ekanite, Ca₂ThSi₈O₂₂

• Nasdala L, Wildner M, Blaimauer D, Zeug M, Chanmuang C, Zoysa EG (2019) Ekanite From Sri Lanka: What Can We Learn From a Radioactive Gemstone? 36th International Gemmological Conference IGC, August 2019, NantArdit M, Cámara F, Hålenius U (2021) Vanadium-induced coloration in grossite (CaAl₄O₇) and hibonite (CaAl₁₂O₁₉). American Mneralogist 106, 599-508.es, France, p106-108.

Optical Spectra of Erythrite, Co₃(AsO₄)₂·8H₂O)

• Faye GH, Nickel EH (1968) The origin of pleochroism in erythrite. The Canadian Minerlogist 9, 494-504.  

Optical Spectra of Eveite, Mn₂(AsO₄)(OH)

• Hålenius U (1998) Manganese valency and the colour of the Mn₂AsO₄(OH) polymorphs eveite and sarkinite. Mineralogical Magazine 52, 113-119.

Optical Spectra of Falcondoite, Ni₄Si₆O₁₅(OH)₂·6H₂O 

• Reddy KM, Moorthy LR, Reddy BJ (1987) Electronic and vibrational absorption spectra in falcondoite. Solid State Communications 64, 1085-1088.

Optical Spectra of Fenaksite, KNaFeSi₄O₁₀ 

• Dorfman MD, Platonov AN, Polshin EV (1978) New data on fenaksite. Trudy Mineralogicheskogo Muzeya, Akademiya Nauk SSSR 26, 198-200. (In Russian)

Optical Spectra of Ferrimolybdite, Fe₂(MoO₄)₃·7H₂O 

• Platonov AN, Polshin EV, Gevorkyan SV, Tarashchan AN (1972) Spectroscopic study of ferrimolybdite. Konstitutsiya i Svoistva Mineralov 6, 62-6. (In Russian)

Optical Spectra of Fluocerite, (Ce,La)F₃

• Gorobets BS, Rogozhin AA, Ryabenko SV (1989) Determination of rare-​earth minerals under unfiltered light from a mercury lamp. Mineralogicheskii Zhurnal 11, 55-7.(In Russian)

Optical Spectra of Fluorcarletonite, KNa₄Ca₄Si₈O₁₈(CO₃)₄·H₂O 

• Gorobets BS, Rogozhin AA, Ryabenko SV (1989) Fluorcarletonite - A New Blue Gem Material. The Journal of Gemmology 38, 376-385.
  

Optical Spectra of Friedelite, Mn₈Si₆O₁₅(OH)₁₀ 

• Reddy SL, Reddy KM, Ramesh K, Reddy BJ (1988) Spectral studies of manganese(2+) in friedelite. Solid State Communications 66, 1169-1171.

Optical Spectra of Gadolinite, Ce₂Fe²⁺Be₂O₂(SiO₄)₂

• Platonov AN, Krasilshchikova OA, Tarashchan AN (1975) Optical absorption of rare earth ions in minerals. Konstitutsiya i Svoistva Mineralov 9, 58-64. (In Russian)

Optical Spectra of Gahnite

• Hålenius U, Andreozzi GB, Skogby H (2010) Structural relaxation around Cr³⁺ and the red-​green color change in the spinel (sensu stricto)​-​magnesiochromite (MgAl₂O₄- ​MgCr₂O₄) and gahnite-​zincochromite (ZnAl₂O₄- ​ZnCr₂O₄)  solid-solution series. American Mineralogist 95, 456-462.  
• Hain M, Sun Z (2019) Blue gahnite from Nigeria. Gems & Gemology 55, 434-436.  

Optical Spectra of Galaxite, MnAl₂O₄

• Hålenius U, Bosi F, Skogby H (2007) Galaxite, MnAl₂O₄, a spectroscopic standard for tetrahedrally coordinated Mn²⁺ in oxygen-based mineral structures. American Mineralogist 92, 1225–1231.

Optical Spectra of Gagarinite, NaCaCeF₆ 

• Gorobets BS, Rogozhin AA, Ryabenko SV (1989) Determination of rare-​earth minerals under unfiltered light from a mercury lamp. Mineralogicheskii Zhurnal 11, 55-7. (In Russian)
  

Optical Spectra of Garnierite, a mixture of chrysotile and lizardite

• Faye GH (1971) A semi-quantitative microscope technique for measuring the optical absorption spectra of mineral and other powders. Canadian Mineralogist 9, 889-895.
• Lakshman SVJ, Reddy BJ  (1973) Optical absorption spectrum of nickel(2+) in garnierite. Proceedings - Indian Academy of Sciences, Section A, 77, 269-78.
• Faye GH (1974) Optical absorption spectrum of nickel(2+) in garnieriteL A discussion. Canadian Mineralogist 12, 389-393
• Reddy BJ, Lakshman SVJ (1975) Optical absorption spectrum of nickel(2+) in garnierite. Comments. Canadian Mineralogist  13, 300-301.

Optical Spectra of Gaspeite, NiCO₃

• Reddy BJ, Frost RL (2004) Electronic and vibrational spectra of gaspeite. Neues Jahrbuch für Mineralogie-Monatschefte 2004, 525-536.

Optical Spectra of Genthelvite, Be₃Zn₄(SiO₄)₃S 

• Rossman GR, Taran MN (2001) Spectroscopic standards for four- and fivefold-coordinated Fe²⁺ in oxygen-based minerals. American Mineralogist 86, 896–903. 
• Hålenius U (2011) Absorption of light by exchange coupled pairs of tetrahedrally coordinated divalent manganese in the helvite-genthelvite solid solution. Periodico di Mineralogia 80, 105-111. 

Optical Spectra of Getchellite, SbAsS₃ 

• Gevorkyan SV, Platonov AN, Povarennykh AS (1967) Color of getchellite. Mineralogicheskii Sbornik (Lvov) 21, 263-8. (In Russian)

Optical Spectra of Glaucochroite, CaMn(SiO₄)

• Keester KL, White WB (1966) Crystal field spectra and chemical  bonding in manganese minerals. In: Papers and proceedings of the fifth general meeting, International Mineralogical Association. Cambridge, England, Aug 30-Sep 3, 1966. p22-35.

Optical Spectra of 'Glauconite', (K,Na)(Fe,Al,Mg)₂(Si,Al)₄O₁₀(OH)₂

• Hradil D, Grygar T, Hrušková M, Bezdicka P, Lang K, Schneeweiss O, Chvátal M (2004) Green Earth Pigment from the Kadan Region, Czech Republic: Use of Rare Fe-rich Smectite. Clays and Clay Minerals 52, 767–778. 
• Sanchez-Navas A, Martin-Algarra A, Eder V, Reddy BJ, Nieto F, Zanin YN (2008) Color, Mineralogy and Composition of Upper Jurassic West Siberian Glauconite: Useful Indicators of Paleoenvironment. The Canadian Mineralogist 46, 1249-1268.

Optical Spectra of Gormanite, Fe₃Al₄(PO₄)(OH)·2H₂O

• Chandrasekhar AV, Ramanaiah MV, Reddy BJ, Reddy YP, Rao PS, Ravikumar RVSSN (2003) Optical and EPR studies of iron bearing phosphate minerals: satterlyite and gormanite from Yukon Territory, Canada. Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 59, 2115-2121. 

Optical Spectra of Graemite, Cu(TeO₃)·H₂O 

• Frost, Ray L, Reddy BJ, Keeffe EC (2010) An application of near-infrared and mid-infrared spectroscopy to the study of selected minerals. Radiation Effects and Defects in Solids, 165(3). pp. 193-205.

Optical Spectra of Grossite, CaAl₄O₇ 

• Ardit M, Cámara F, Hålenius U (2021) Vanadium-induced coloration in grossite (CaAl₄O₇) and hibonite (CaAl₁₂O₁₉). American Mneralogist 106, 599-508.

Optical Spectra of Guilleminite, Ba(UO₂)₃(SeO₃)₂O₂·3H₂O

• Frost RL, Reddy BJ, Dickfos MJ (2008) An application of near-infrared and mid-infrared spectroscopy to the study of uranyl selenite minerals: derriksite, demesmaekerite, guilleminite and haynesite. Journal of Near Infrared Spectroscopy 16, 455-469.

Optical Spectra of 'Hackmanite', Na₈Al₆Si₆O₂₄(Cl₂,S) - Sodalite Group

• Ballentyne DWG, Bye KL (1970) The nature of photochromism in chlorosodalites from optical data. Journal of Physics D: Applied Physics 3, 1438-1443.
• Belichenko VP, Mazykin VV, Platonov AN, Tarashchan AN (1973) Paramagnetic sulfur radicals in dark-colored hackmanites and natural lazurites. Dopovidi Akademii Nauk Ukrains'koi RSR, Seriya B:  Geologiya, Geofizika, Khimiya ta Biologiya 35, 99-101. (In Ukranian) 
• Chang IF (1974) Synthesis of photochromic and cathodochromic sodalite. Journal of the Electrocheical Society 121, 815-820.
• Kondo D, Beaton D (2009) Hackmanite/sodalite from Myanmar and Afghanistan. Gems & Gemology 45, 38-43.
• Blumentritt F, Fritsch E (2021) Photochromism and Photochromic Gems: A Review and Some New Data (Part 1). The Journal of Gemmology 37,780-800.

Optical Spectra of Halloysite, Al₂(Si₂O₅)(OH)₄

• Gritsaenko GS, Grum-Grzhimailo SV (1959) Chromium-bearing halloysite from Aidyrlinsk, Southern Urals. Zapiski Vserossiiskogo Mineralogicheskogo Obshchestva  78, 61-3. (In Russian)

Optical Spectra of Hammarite, Pb₂Cu₂Bi₄S₉

• Platonov AN, Tarashchan AN, Povarennykh AS (1972) Optical spectroscopy of vanadium in natural minerals.  II.  Optical absorption spectra of vanadates with complex radicals. Konstitutsiya i Svoistva Mineralov 6, 58-62. (In Russian)

Optical Spectra of Haradaite, SrVSi₂O₇

• Platonov AN, Tarashchan AN (1973) Optical spectroscopy of vanadium in natural minerals.  III.  Absorption spectra of vanadium(4+) and vanadium(3+) complexes. Konstitutsiya i Svoistva Mineralov 7, 75-81. (In Russian)

Optical Spectra of Haynesite, (UO₂)₃(OH)₂(SeO₃)₂·5H₂O  

• Frost RL, Reddy BJ, Dickfos MJ (2008) An application of near-infrared and mid-infrared spectroscopy to the study of uranyl selenite minerals: derriksite, demesmaekerite, guilleminite and haynesite. Journal of Near Infrared Spectroscopy 16, 455-469.

Optical Spectra of Hedyphane, Ca₂Pb₃(AsO₄)₃Cl

• Frost RL, Palmer SJ, Reddy BJ (2008) The structure of mimetite, arsenian pyromorphite and hedyphane –a Near Infrared spectroscopic study. Polyhedron 27, 1747-1753. 

Optical Spectra of Hewettite, CaV₆O₁₆·9H₂O

• Platonov AN, Tarashchan AN, Povarennykh AS (1972) Optical spectroscopy of vanadium in natural minerals.  II.  Optical absorption spectra of vanadates with complex radicals. Konstitutsiya i Svoistva Mineralov 6, 58-62. (In Russian)
• Platonov AN, Tarashchan AN (1973) Optical spectroscopy of vanadium in natural minerals.  III.  Absorption spectra of vanadium(4+) and vanadium(3+) complexes. Konstitutsiya i Svoistva Mineralov 7, 75-81. (In Russian)

Optical Spectra of Hiärnerite, Ca₂Zr₄Mn³⁺SbTiO₁₆

• Holtstam D (1997) Hiärnerite, a new Zr-Sb oxide mineral isostructural with calziritite, from Langban, Sweden. European Journal of Mineralogy 9, 843-848.
  

Optical Spectra of Hübernite, Mn(WO₄)

• Keester KL, White WB (1966) Crystal field spectra and chemical  bonding in manganese minerals. In: Papers and proceedings of the fifth general meeting, International Mineralogical Association. Cambridge, England, Aug 30-Sep 3, 1066. p22-35.

Optical Spectra of Humite, (Mg,Fe)₇(SiO₄)₃(F,OH)₂

• Sharma KBN, Reddy BJ, Moorthy LR, Vedanand S, Sudhana BM (1990) Moessbauer, ESR and optical spectra of humite mineral. Pakistan Journal of Scientific and Industrial Research 33, 480-483.
• Sharma KBN, Madhusudhana B, Reddy BJ, Vedanand S, Srinivasulu G (1991) Optical and ESR studies of iron(2+)​, iron(3+) and manganese(2+) ions in humite. Solid State Communications 78, 751-754.   
• Langer K, Platonov AN, Matsyuk SS, Wildner M (2002) The crystal chemistry of the humite minerals: Fe²⁺-Ti⁴⁺ charge transfer and structural allocation of Ti⁴⁺ in chondrodite and clinohumite. European Journal of Mineralogy 14, 1027–1032. 

Optical Spectra of Hydroxylherderite, CaBePO₄OH

• Cathelineau T (2019) Purple hydroxylherderite from Brazil. The Journal of Gemmology 36, 501-503. 

Optical Spectra of Inesite, Ca₂Mn²⁺₇Si₁₀O₂₈(OH)₂·5H₂O

• Keester KL, White WB (1966) Crystal field spectra and chemical  bonding in manganese minerals. In: Papers and proceedings of the fifth general meeting, International Mineralogical Association. Cambr.idge, England, Aug 30-Sep 3, 1066. p22-35.

Optical Spectra of Iowaite, Mg₆Fe₂(OH)₁₆Cl₂·4H₂O

• Reddy SL, Maheswaramma KS, Reddy GS, Frost RL, Endo T (2010) Optical absorption, infrared, Raman, and EPR spectral studies on natural iowaite mineral. Transition Metal Chemistry (Dordrecht, Netherlands) 35, 331-336. 

Optical Spectra of Kämmererite, Mg₅Al(AlSi₃O₁₀)(OH)₈

• Andrut M, Wildner M, Taran M, Langer K, Schulz R (1996) Temperature dependent polarized single crystal absorption spectra of kaemmererite. Physics and Chemistry of Minerals 23, 242-243.
  

Optical Spectra of Karrooite, MgTi₂O₅

• Llusar M, García E, García MT, Gargori C, Badenes JA, Monrós G (2015) Synthesis, stability and coloring properties of yellow–orange pigments based on Ni-doped karrooite (Ni,Mg)Ti₂O₅. Journal of the European Ceramic Society 35, 357–376.

Optical Spectra of "Kerchenite", an iron phosphate mixture

• Platonov AN, Polshin EV, Tarashchan AV, Vorobev IB (1972) Moessbauer and optical spectroscopy of iron in some natural phosphates. Mineralogicheskii Sbornik (Lvov) 26, 257-68. (In Russian)  

Optical Spectra of Kerolite, Mg₃Si₄O₁₀(OH)₂·H₂O

• Brindley GW, Bish DL, Wan HM (1979) Compositions, structures, and properties of nickel-containing minerals in the kerolite-pimelite series. American Mineralogist 64, 615-625.  

Optical Spectra of 'Knebelite', (FeMn)₂SiO₄

• Burns RG (1970) Mineralogical Applications of Crystal Field Theory. Cambridge University Press, Cambridge.
  

Optical Spectra of Lamprophyllite, (SrNa)Ti₂Na₃Ti(Si₂O₇)₂O₂(OH)₂

• Reddy BJ, Yamauchi J, Reddy YP, Ravikumar RVSSN, Chandrasekhar AV, Venkataramanaiah M (2002) Optical and EPR spectra of Ti³⁺ in lamprophyllite from Kola Peninsula, Russia. Neues Jahrbuch für Mineralogie, Monatshefte (2002), 138-144.

Optical Spectra of Langbeinite, K₂Mg₂(SO₄)₃

• Percival MJL (1990) Optical absorption spectroscopy of doped materials: the P2₁3-P2₁2₁2₁ phase transition in K₂(Cd_0.98Co_0.02)₂(SO₄)₃. Mineralogical Magazine 54, 525-536.

Optical Spectra of 'Lapis Lazuli'

• Faye GH (1971) A semi-quantitative microscope techique for measuring the optical absorption spectra of mineral and other powders. The Canadian Mineralogist 10, 889-895. 
• Scarratt K (1986) Notes from the The Laboratory. Journal of Gemmology 20, 35-39.

Optical Spectra of Laurentthomasite, KMg₂AlBe₂Si₁₂O₃₀

• Ounorn P, Srisataporn B, Suphan C (2020) Laurentthomasite, a New Gem Mineral. The Journal of Gemmology 37, 136-139.
• Pignatelli I, Ferraris C, Schaniel D (2023) Origin of the Colour and Dichroism in Laurentthomasite. The Journal of Gemmology 38, 708-714.
  

Optical Spectra of Lazurite, Na₃Ca(Si₃Al₃)O₁₂S 

• Faye GH (1971) A Semi-quantitative MIcroscope Technique for Measuring the Optical Absorption Spectr of Mineral and Other Powders. The Canadian Mineralogist   889-895
• Belichenko VP, Mazykin VV, Platonov AN, Tarashchan AN (1973) Paramagnetic sulfur radicals in dark-colored hackmanites and natural lazurites. Dopovidi Akademii Nauk Ukrains'koi RSR, Seriya B:  Geologiya, Geofizika, Khimiya ta Biologiya 35, 99-101. (In Ukranian)
• Tauson VL, Goettlicher J, Sapozhnikov AN, Mangold S, Lustenberg E (2012) Sulphur speciation in lazurite-type minerals (Na,Ca)8[Al6Si6O24](SO4,S)2 and their annealing products: a comparative XPS and XAS study. European Journal of Mineralogy 24, 133-152.
• Farsang S, Caracas R, Adachi TBM, Schnyder C, Zajack Z (2023) S₂^– and S₃^– radicals and the S₄^2– polysulfide ion in lazurite, haüyne, and synthetic ultramarine blue revealed by resonance Raman spectroscopy. American Mineralogis 108, 2234-2243.  

Optical Spectra of Leucophoenicite, Mn₇(SiO₄)₃(OH)₂

• Keester KL, White WB (1966) Crystal field spectra and chemical  bonding in manganese minerals. In: Papers and proceedings of the fifth general meeting, International Mineralogical Association. Cambridge, England, Aug 30-Sep 3, 1066. p22-35.

Optical Spectra of Libethenite, Cu₂(PO₄)(OH)

• Reddy SN, Ravikumar RVSSN, Reddy BJ, Rao PS ( 1995) Optical and EPR spectra of libethenite mineral. Ferroelectrics 166, 55-62.

Optical Spectra of Linarite, PbCu(SO₄)(OH)₂

• Sudhana SM, Reddy BJ, Vedanand S, Reddy YP, Rao PS (1995) Spectroscopic studies on Cu(II) bearing linarite, CuPbSO₄(OH)​₂. Radiation Effects and Defects in Solids 133, 217-224. 
• Babonas GJ, Maltsev V, Reza A, Baran M, Deyev S, Shvanskaya L, Kindurys A, Vaisnoras R (2001) Structural determination of optical properties in cuprates. Lithuanian Journal of Physics 41, 299-304. 
• Babonas GJ, Szymczak R, Baran M, Reza A, Maltsev V, Sabataityte J, Dyeyev S (2002) Structural determination of physical properties in cuprates.Crystal Engineering 5, 209-216.  

Optical Spectra of Lithiophilite, LiMn(PO₄)

• Keester KL, White WB (1966) Crystal field spectra and chemical  bonding in manganese minerals. In: Papers and proceedings of the fifth general meeting, International Mineralogical Association. Cambridge, England, Aug 30-Sep 3, 1066. p22-35.

Optical Spectra of Lovchorrite, (◻,Ca,Na)₃(Ca,REE)₄Ti(Si₂O₇)₂[H₂O,OH,F]₄·H₂O

• Platonov AN, Krasilshchikova OA, Tarashchan AN (1975) Optical absorption of rare earth ions in minerals. Konstitutsiya i Svoistva Mineralov 9, 58-64. (In Russian)

Optical Spectra of Leucopoenicite, Mn₇(SiO₄)₃(OH)₂

• Lakshmi RS, Padma SK, Udayabhaska RG, Endo T, Frost RL (2014) Spectroscopic characterization of manganese minerals. Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 117, 270-5. 

Optical Spectra of Ludlamite, Fe₃(PO₄)₂•4H₂O

• Cathelineau T (2024) Ludlamite from Brazil. The Journal of Gemmology 39, 205-205.

Optical Spectra of Magnesioferrite, MgFe₂O₄

• Andreozzi GB. Hålenius U, Skogby H (2001) Spectroscopic active ^IVFe³⁺-^VIFe³⁺ clusters in spinel-magnesioferrite solid solution crystals: a potential monitor for ordering in oxide spinels. Physics and Chemistry of Minerals 28, 435-444.

Optical Spectra of Magnesite, MgCO₃

• Reddy RR, Reddy SL, Reddy GS, Reddy BJ (2000) Optical absorption and EPR spectra of magnesite mineral. Radiation Effects and Defects in Solids 153, 53-58.

Optical Spectra of Magnussonite, Mn₁₀As₆O₁₈(OH,Cl)₂

• Hålenius U, Lindqvist B (1994) Chromophoric divalent iron in optically anisotropic magnussonite. European Journal of Mineralogy 8, 25-34.
  

Optical Spectra of Majorite, Mg₃(MgSi)(SiO₄)₃

• Keppler H, McCammon CA (1996) Crystal field and charge transfer spectrum of (Mg, Fe)SiO₃ majorite.  Physics and Chemistry of Minerals 23, 94–98

Optical Spectra of Malachite, Cu₂CO₃(OH)₂

• Lakshman SVJ, Reddy BJ (1973) Optical Absorption Spectra of Cu²⁺ in Chalcanthite and Malchite. Canadian Mineralogist 12, 207-210.
• Babonas GJ, Maltsev V, Reza A, Baran M, Deyev S, Shvanskaya L, Kindurys A, Vaisnoras R (2001) Structural determination of optical properties in cuprates. Lithuanian Journal of Physics 41, 299-304. 
• Babonas GJ, Szymczak R, Baran M, Reza A, Maltsev V, Sabataityte J, Dyeyev S (2002) Structural determination of physical properties in cuprates.Crystal Engineering 5, 209-216.  
• Peng SS, Chen TH, Chen JJ (2008) Investigation on the local structure, optical absorption spectra of malachite and azurite. Guisuanyan Tongbao 27, 1040-1043, 1047.  (In Chinese) 
• Klokishner S, Behrens M, Reu O, Tzolova-Muller G, Girgsdies F, Trunschke A, Schlogl R (2011) Cation Ordering in Natural and Synthetic (Cu_{1- ​x}Zn_x)​₂CO₃(OH) ​2 and (Cu_1-​xZn_x)​₅(CO₃) ​₂(OH)​₆. Journal of Physical Chemistry A, 115, 9954-9968.   

Optical Spectra of Melanocerite, (Ce,Ca)₅(SiO₄,BO₄)₃(OH,O)

• Gorobets BS, Rogozhin AA, Ryabenko SV (1989) Determination of rare-​earth minerals under unfiltered light from a mercury lamp. Mineralogicheskii Zhurnal 11, 55-7. (In Russian) 

Optical Spectra of Melanterite, FeSO₄·7H₂O

• Reddy SN, Rao PS, Ravikumar RVSSN, Reddy BJ, Reddy YP (2001) Spectral investigations on melanterite mineral from France. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 57, 1283-128.7  

Optical Spectra of Meta-autunite, Ca(UO₂)₂(PO₄)₂·6H₂O

• Platonov AN, Povarennykh AS, Tarashchan AN Bondar VV (1972) Effect of crystal chemical factors on the optical absorption spectra of uranyl ion in minerals. Mineralogicheskii Sbornik (Lvov) 26, 393-398. (In Russian)
• Matkovskii AO, Platonov AN, Tarashchan AN, Sidorenko GA (1980)  New data on the luminescence and spectroscopy of meta-autunite. Mineralogicheskii Zhurnal  2, 46-53. (In Russian)
• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of Metahewettite, CaV₆O₁₆·3H₂O

• Platonov AN, Tarashchan AN, Povarennykh AS (1972) Optical spectroscopy of vanadium in natural minerals.  II.  Optical absorption spectra of vanadates with complex radicals. Konstitutsiya i Svoistva Mineralov 6, 58-62. (In Russian)

Optical Spectra of Metatorbernite, Cu(UO₂)₂(PO₄)₂·8H₂O

• Platonov AN, Povarennykh AS, Tarashchan AN Bondar VV (1972) Effect of crystal chemical factors on the optical absorption spectra of uranyl ion in minerals. Mineralogicheskii Sbornik (Lvov) 26, 393-398. (In Russian)
• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of Metauranocircite-I, Ba(UO₂)₂(PO₄)₂·6H₂O  

• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of Metauranospinite, Cu(UO₂)₂(AsO₄)₂·8H₂O  

• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of Metazeunerite, Cu(UO₂)₂(AsO₄)₂·8H₂O  

• Billing DE, Hathaway BJ, Nicholls P (1969) Polarizations of the copper(II) and uranyl electronic spectra of meta-zeunerite single crystals. Journal of the Chemical Society (A), 316-319. 
• Platonov AN, Povarennykh AS, Tarashchan AN Bondar VV (1972) Effect of crystal chemical factors on the optical absorption spectra of uranyl ion in minerals. Mineralogicheskii Sbornik (Lvov) 26, 393-398. (In Russian)

Optical Spectra of Mimetite, Pb₅(AsO₄)₃Cl

• Platonov AN, Tarashchan AN (1973) Optical absorption of tetrahedral complexes of chromium in some minerals with apatite structure. Doklady Akademii Nauk SSSR 209, 929-32. (In Russian)

Optical Spectra of Mitridatite, Ca₂Fe₃O₂(PO₄)₃·3H₂O  

• Platonov AN, Polshin EV, Tarashchan AV, Vorobev IB (1972) Moessbauer and optical spectroscopy of iron in some natural phosphates. Mineralogicheskii Sbornik (Lvov) 26, 257-68. (In Russian)
• Frost RL, Palmer SJ, Reddy BJ (2008) The structure of mimetite, arsenian pyromorphite and hedyphane –a Near Infrared spectroscopic study. Polyhedron 27, 1747-1753. 

Optical Spectra of Mosandrite, (Ca₃REE)[(H₂O)₂Ca_0.5[]_0.5]Ti(Si₂O₇)₂(OH)₂(H₂O)₂ 

• Henn U, Schmitz F (2015) Gem mosandrite from Russia. The Journal of Gemmology 34, 565-566.

Optical Spectra of Musgravite, BeMg₂Al₆O₁₂

• Zhao Z, Kitawaki H, Emori (2023) A Remarkable Cr-bearing Red Musgravite. The Journal of Gemmology 38, 548-551 

Optical Spectra of Natrolite, Na₂(Si₃Al₂)O₁₀·2H₂O

• Li YH, Chen HF, Lin SH (2020) A new deposit of pink natrolite from Indonesia. Gems & Gemology 56, 309-311. 

Optical Spectra of Népouite, Ni₃Si₂O₅(OH)₄

• Reddy BJ, Frost RL, Dickfos MJ (2009) Characterisation of Ni silicate-bearing minerals by UV–vis–NIR spectroscopy. Effect of Ni substitution in hydrous Ni–Mg silicates. Spectrochimica Acta Part A 71, 1762–1768. 

Optical Spectra of Nickelblödite, Na₂Mg(SO₄)₂·4H₂O 

• Venkata RM, Srinivasulu G, Ravikumar RVSSN, Vedanand S, Reddy BJ (1996) Electronic and vibrational absorption spectra in nickelblodite. Indian Journal of Physics B, 70B, 87-92.

Optical Spectra of Nullaginite, Ni₂(CO₃)(OH)₂

• Frost RL, Keeffe EC, Reddy BJ (2010) Characterisation of Ni carbonate-bearing minerals by UV-Vis-NIR spectroscopy. Transition Metal Chemistry 35, 279-287.

Optical Spectra of Olivenite, Cu₂(AsO₄)(OH)

• Chandrasekhar AV, Venkataramanaiah M, Ravikumar RVSS, Reddy BJ, Reddy YP (1997) Electronic spectra of pseudomalachite and olivenite. Indian Journal of Pure and Applied Physics 35, 71-72.

Optical Spectra of Opal, SiO₂·nH₂O

• Fritsch E, Megaw PKM, Spano TL, Chauvire B, Rondeau B, Gray M, Hainschwang T, Renfro N (2015) Green-luminescing hyalite opal from Zacatecas, Mexico. The Journal of Gemmology 34, 490-508.
• Feral K (2022) Chromiuim-bearing Translucent Green Common Opal. The Journal of Gemology 38, 120-122.
• Wu J, Ma H, Li H (2022) An  Unusual Pink Synthetic Opal. The Journal of Gemology 38, 132-133.

Optical Spectra of Otwayite, Ni₂(CO₃)(OH)₂·H₂O

• Reddy KM, Jacob AS, Reddy BJ (1986) Electronic and vibrational absorption spectra in otwayite, a new nickel mineral. Physics Letters A 115, 182-185.

Optical Spectra of Oxykerchenite, BaMg₂TiO₂(Si₂Al₂)O₁₀

• Platonov AN, Polshin EV, Tarashchan AV, Vorobev IB (1972) Moessbauer and optical spectroscopy of iron in some natural phosphates. Mineralogicheskii Sbornik (Lvov) 26, 257-68. (In Russian)
  

Optical Spectra of Pascoite, Ca₃V₁₀O₂₈·17H₂O

• Platonov AN, Tarashchan AN, Povarennykh AS (1972) Optical spectroscopy of vanadium in natural minerals.  II.  Optical absorption spectra of vanadates with complex radicals. Konstitutsiya i Svoistva Mineralov 6, 58-62. (In Russian)
• Reddy GU, Reddy RR, Reddy SL, Frost RL, Endo T (2011) Spectroscopic and structural characterization of pascoite. Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 79, 1402-1405.     

Optical Spectra of Parsonite, Pb₂(UO₂)(PO₄)₂

• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of Pecoraite, Ni₃Si₂O₅(OH)₄  

• Reddy BJ, Frost RL, Dickfos MJ (2009) Characterisation of Ni silicate-bearing minerals by UV–vis–NIR spectroscopy. Effect of Ni substitution in hydrous Ni–Mg silicates. Spectrochimica Acta Part A 71, 1762–1768. 

Optical Spectra of Pectolite, NaCa₂Si₃O₈(OH)

• Zheng C; Yin ZW, Yin K, Li Y, Chen QL (2013) Mineralogical and spectral characteristics of copper pectolite. Guang pu xue yu guang pu fen xi 33, 1977-1981 (In Chinese).
• Huang HM, Shih YH, Chen HF, Lee HY, Fang JN, Shen CC, Yu BS (2023) Revealing the Secrets behind the Color and Sea-Wave Patterns
  of Larimar. Minerals 13, 1221. 
  

Optical Spectra of Periclase, MgO

• Keppler H, Kantor I, Dubrovinsky LS (2007) Optical absorption spectra of ferropericlase to 84 GPa. American Mineralogist 92, 433-436.

Optical Spectra of Phosphophyllite, Zn₂Fe(PO₄)₂·4H₂O

• Chen X, Wang J, Chen Y, Gao S (2022) Gemmological and mineralogical characteristics of light blue-green phosphophyllite from Bolivia Journal of Gems & Gemmology 24, 18-25. (In Chinese)

Optical Spectra of Phosphuranylite, KCa(H₃O)₃(UO₂)₇(PO₄)₄O₄·8H₂O

• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of "Picite", ~CaFe₄(PO₄,SO₄)₂(OH)₈·4-6H₂O

• Platonov AN, Polshin EV, Tarashchan AV, Vorobev IB (1972) Moessbauer and optical spectroscopy of iron in some natural phosphates. Mineralogicheskii Sbornik (Lvov) 26, 257-68. (In Russian)

Optical Spectra of Piemontite, Ca₂Al₂Mn(Si₂O₇)(SiO₄)O(OH)

• Abu-Eid RM (1976) Absorption spectra of transition metal-​bearing minerals at high pressures. RGJ Strens, editor. Physics and Chemisry of Minerals and Rocks, NATO Advanced Study Institute. "Petrophys." (1976), 641-75.
• Langer K, Abu-Eid RM. Anastasiov P (1976) Absorptoin spektren synthetischer Piemontint in den Bereichen 43000-11000 cm^{- ​1} (2.5-40 m.).  Zeitschrift für Kristallographie 144, 434-436.
• Langer K, Abu-Eid RM (1977) Measurement of the polarized absorption spectra of synthetic transition metal-​bearing silicate microcrystals in the spectral range 44,​000-​4,​000 cm^-​1. Physics and Chemistry of Minerals 1, 273-299.
• Kersten M, Langer K, Almen H, Tillmanns E (1988) The polarized single crystal spectra and structures of thetic thulite and piemontites, Ca₂Al_3-pMn³⁺[O/OH/SiO/SiO], with 0.5 < p < 1.6. Zeitschrift für Kristallographie 185, 111.
• Platonov AN, Sachanbinski M, Szujszkiewicz A, Sedenko VS (1998) Purple-red colour of quartz caused by piemontite inclusions. Zeitschrift Dt Gemmol Ges 47. 193-198.
  
• Langer K, Tillmanns E, Kersten M, Almen H, Arni RK (2002) The crystal chemistry of Mn3+ in the clino- and orthozoisite structure types, Ca₂M₃³⁺[OH|O|SiO₄|Si₂O₇]: A structural and spectroscopic study of some natural piemontites and “thulites” and their synthetic equivalents. Zeitschrift für Kristallographie 217, 563-580.

Optical Spectra of Pimelite, Ni₃Si₄O₁₀(OH)₂·4H₂O

• Brindley GW, Bish DL, Wan HM (1979) Compositions, structures, and properties of nickel-containing minerals in the kerolite-pimelite series. American Mineralogist 64, 615-625.  
• Reddy BJ, Frost RL, Dickfos MJ (2009) Characterisation of Ni silicate-bearing minerals by UV–vis–NIR spectroscopy. Effect of Ni substitution in hydrous Ni–Mg silicates. Spectrochimica Acta Part A 71, 1762–1768. 

Optical Spectra of Plancheite. Cu₈(Si₈O₂₂)(OH)₄·H₂O 

• Sarma KBN, Reddy BJ, Lakshman SVJ (1982) Absorption spectra of copper(2+) in shattuckite and plancheite. Physics Letters A, 92A, 305-308.
• Sarma KBN, Reddy BJ, Lakshman SVJ (1984) EPR and optical spectra of certain copper-​bearing minerals:  a tool to probe site symmetry of copper(II) ion. Proceedings of the Nuclear Physics and Solid State Physics Symposium (1984), 25, 209-10.  

Optical Spectra of Polydymite, NiNi₂S₄

• Vedanand S, Reddy BJ, Reddy YP (1994) Spectroscopic investigations on polydymite. Radiation Effects and Defects in Solids 128, 257-262.  
  

Optical Spectra of Poudretteite, KNa₂B₃Si₁₂O₃₀

• Smith CP, Bosshart G, Graeber S , Hänni H, Günther D , Hametner K, Gübelin EJ (2003) Poudretteite: A rare gem species from Mogok Valley Gems & Gemology, Spring, 24-31.

Optical Spectra of Prehnite, Ca₂Al₂Si₃O₁₀(OH)₂ 

• Reddy SN, Rao PS, Ravikumar RVSSN, Reddy BJ (2001) EPMA, optical, EPR, and IR spectral studies of prehnite mineral. Indian Journal of Physics, A 75A, 429-432.  
• Reddy NCG, Fayazyddin SM, Reddy RRS, Reddy GS, Reddy SL, Rao PS, Reddy BJ (2005) Characterisation of prehnite by EPMA, Mössbauer, optical absorption and EPR spectroscopic methods. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 62, 71-75.  

Optical Spectra of Proustite, Ag₃AsS₃ 

• Gevorkyan CV, Platonov AN, Povarennykh,AS (1967) Colors of proustite and pyrargyrite. Dopovidi Akademii Nauk Ukrains'koi RSR, Seriya B:  Geologiya, Geofizika, Khimiya ta Biologiya 29, 599-601. (In Ukranian)

Optical Spectra of Pseudomalachite, Cu₅(PO₄)₂(OH)₄ 

• Chandrasekhar AV, Venkataramanaiah M, Ravikumar RVSS, Reddy BJ, Reddy YP (1997) Electronic spectra of pseudomalachite and olivenite. Indian Journal of Pure and Applied Physics 35, 71-72.

Optical Spectra of Pucherite, BiVO₄ 

• Platonov AN, Tarashchan AN, Povarennykh AS (1972) Optical spectroscopy of vanadium in natural minerals.  II.  Optical absorption spectra of vanadates with complex radicals. Konstitutsiya i Svoistva Mineralov 6, 58-62. (In Russian)
• Platonov AN, Tarashchan AN (1973) Optical spectroscopy of vanadium in natural minerals.  III.  Absorption spectra of vanadium(4+) and vanadium(3+) complexes. Konstitutsiya i Svoistva Mineralov 7, 75-81. (In Russian)

Optical Spectra of Pyrargyrite, Ag₃SbS₃ 

• Gevorkyan CV, Platonov AN, Povarennykh,AS (1967) Colors of proustite and pyrargyrite. Dopovidi Akademii Nauk Ukrains'koi RSR, Seriya B:  Geologiya, Geofizika, Khimiya ta Biologiya 29, 599-601. (In Ukranian)
• Rossman GR (1988) Optical Spectroscopy. In: F.C. Hawthorne, ed., Spectroscopic Methods in Mineralogy and Geology. Reviews in Mineralogy 18, 207-254.

Optical Spectra of Pyrite, FeS₂ 

• Horita H (1980)  Some optical properties of natural pyrite crystals as a semiconductor. Science Reports of the Research Institutes, Tohoku University, Series A:  Physics, Chemistry, and Metallurgy 29, 112-121. 

Optical Spectra of Pyromorphite, Pb₅(PO₄)₃Cl 

• Levy M, M'Hamdi O (1970) Description provisoire on Sommaire des especes Minerales du Maroc - 17 Pyromorphite. Notes du Service géologique, Protectorat de la Répubilique Frncaise au Maroc, Direction de la production industrielle et des mines, Division des mines et de la géologie, Servic. 30, 195-199.
• Platonov AN, Tarashchan AN (1973) Optical absorption of tetrahedral complexes of chromium in some minerals with apatite structure. Doklady Akademii Nauk SSSR 209, 929-32. (In Russian)
• Ma Hy, Cui DA, Qin ZL, He Z, Mu SC (2006) Spectroscopic characterization of the rare mineral-pyromorphite. Acta Mineralogica Sinica 25, 165-168. (In Chinese)
• Frost RL, Palmer SJ, Reddy BJ (2008) The structure of mimetite, arsenian pyromorphite and hedyphane –a Near Infrared spectroscopic study. Polyhedron 27, 1747-1753.
• Reddy BJ, Frost RL, Palmer SJ (2008) A Near Infrared spectroscopic study of the phosphate mineral pyromorphite Pb₅(PO4)₃Cl. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 71, 430-435.  

Optical Spectra of Pyrophanite, MnTiO₃

• Keester KL, White WB (1966) Crystal field spectra and chemical  bonding in manganese minerals. In: Papers and proceedings of the fifth general meeting, International Mineralogical Association. Cambridge, England, Aug 30-Sep 3, 1066. p22-35.

Optical Spectra of Pyroxmangite, MnSiO₃ 

• Manning PG (1968b) Absorption spectra of the manganese-bearing chain silicates pyroxmangite, rhodonite, bustamite and serandite. Canadian Mineralogist 9, 348-357.

Optical Spectra of Renierite, (Cu,Zn)₁₁Fe₄(Ge,As)₂S₁₆

• Reddy RRS, Fayazuddin M, Reddy GS, Reddy Sl, Rao pS, Reddy BJ, Garcia Fn (2004) Tetrahedral site of Fe(III) and Cu(II) in renierite. Crystal Reseach and Technology 39, 240-244.

Optical Spectra of Rhabdophane, Ce(PO₄)·H₂O  

• Platonov AN, Krasilshchikova OA, Tarashchan AN (1975) Optical absorption of rare earth ions in minerals. Konstitutsiya i Svoistva Mineralov 9, 58-64. (In Russian)

Optical Spectra of Rhodonite, CaMn₃Mn[Si₅O₁₅]

• Keester KL, White WB (1966) Crystal field spectra and chemical bonding in manganese minerals. In: Papers and proceedings of the fifth general meeting, International Mineralogical Association. Cambridge, England, Aug 30-Sep 3, 1066. p22-35.
• Manning PG (1968) Absorption spectra of the manganese-bearing chain silicates pyroxmanganite, rhodonite, bustamite and serandite. Canadian Mineralogist 9, 348-357. 
• Lakshman SVJ, Reddy BJ (1973) Optical absorption spectrum of manganese(2+) in rhodonite. Physica (Amsterdam) (1973), 66(3), 601-10.  
• Lakshman SVJ, Reddy BJ (1973) Accurate method for the measurement of wavelengths of ligand field bands. Proceedings of the Nuclear Physics and Solid State Physics Symposium (1973), 16C, 117.
• Marshall M, Runciman WA (1975) The absorption spectrum of rhodonite. American Mineralogist 60, 88-97.
• Khomenko VM, Bonev I, Mincheva-Stefanova I, Platonov AN (1988) Optical spectra of rhodonites from the skarn ore deposits of Central Rhodope, Bulgaria. Geokhimiya, Mineralogiya i Petrologiya 24, 28-40. (In Russian)
• Zhang YH, Ding YK, Pei JC, Gu YL, Yu MD (2023) Chemical Constituents and Spectra Characterization of Monocrystal Rhodonite From Brazil. Spectroscopy and Spectral Analysis 43, 3504-3508. (in Chinese)
  

Optical Spectra of Ringwoodite

• Keppler H, Smyth JR (2005) Optical and near infrared spectra of ringwoodite to 21.5 GPa: Implications for radiative heat transport in the mantle. American Mineralogist 90, 1209-1212.

Optical Spectra of Rinkite-(Ce), Na₂Ca₄CeTi(Si₂O₇)₂OF₂

• Platonov AN, Krasilshchikova OA, Tarashchan AN (1975) Optical absorption of rare earth ions in minerals. Konstitutsiya i Svoistva Mineralov 9, 58-64. (In Russian)

Optical Spectra of Rinkolite, (◻,Ca,Na)₃(Ca,REE)₄Ti(Si₂O₇)₂[H₂O,OH,F]₄·H₂O

• Gorobets BS, Rogozhin AA, Ryabenko SV (1989) Determination of rare-​earth minerals under unfiltered light from a mercury lamp. Mineralogicheskii Zhurnal 11, 55-7. (In Russian)

Optical Spectra of Rodalquilarite, H₃Fe₂(TeO₃)₄Cl

• Frost RL, Keeffe EC, Reddy BJ (2009) An application of near-infrared and midinfrared spectroscopy to the study of selected tellurite minerals: xocomecatlite, tlapallite and rodalquilarite. Transition Metal Chemistry, 34, 23-32.

Optical Spectra of Rosasite, CuZn(CO₃)(OH)₂ 

• Reddy BJ, Nieto F, Navas AS (2004) Spectroscopic characterisation of rosasite and aurichalcite. Neues Jahrbuch fur Mineralogie-Monatshefte 2004, 302-316.
• Klokishner S, Behrens M, Reu O, Tzolova-Muller G, Girgsdies F, Trunschke A, Schlogl R (2011) Cation Ordering in Natural and Synthetic (Cu_1-​xZn_x)​₂CO₃(OH) ​₂ and (Cu_1-​xZn_x) ​₅(CO₃)​₂(OH) ​₆. Journal of Physical Chemistry A, 115, 9954-9968.   

Optical Spectra of Roscoelite, KV₂(Si₃Al)O₁₀(OH)₂

• Platonov AN, Tarashchan AN (1973) Optical spectroscopy of vanadium in natural minerals. III. Absorption spectra of vanadium(4+) and vanadium(3+) complexes. Konstitutsiya i Svoistva Mineralov 7, 75-81. (In Russian)
• Schmetzer K (1982) Absorptionsspektkroskopie und Farbe von V³⁺-haltigen natürlichen Oxiden und Silikaten - eni Beitrag zur Kristallcheime des Vanadiums. N. Jb Miner. Abh 144, 73-106. 

Optical Spectra of Sabugalite, HAl(UO₂)₄(PO₄)₄·16H₂O

• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of Saléeite, Mg(UO₂)₂(PO₄)₂(H₂O)₁₀

• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of Sarkinite, Mn₂(AsO₄)(OH) 

• Hålenius U (1998) Manganese valency and the colour of the Mn₂AsO₄(OH) polymorphs eveite and sarkinite. Mineralogical Magazine 52, 113-119.

Optical Spectra of Satterlyite, (Fe)₁₂(PO₃OH)(PO₄)₅(OH,O)₆ 

• Chandrasekhar AV, Ramanaiah MV, Reddy BJ, Reddy YP, Rao PS, Ravikumar RVSSN (2003) Optical and EPR studies of iron bearing phosphate minerals: satterlyite and gormanite from Yukon Territory, Canada. Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 59, 2115-2121. 

Optical Spectra of Scorodite, FeAsO₄·2H₂O

• Stephan T, Schmitz, Wild M (2017) Colour-change scorodite from Tsumb, Namibia. The Journal of Gemmology 35, 394-395. 

Optical Spectra of Sekaninite, Fe₂Al₃(AlSi₅O₁₈)    

• Goldman DS, Rossman GR, Dollase WA (1977) Channel constituents in cordierite. American Mineralogist 62, 1144-1157.
• Hanus R, Kusa I, Kasikova J (2016) Gem-quality sekaninaite from the Czech Republic. The Journal of Gemmologoy 35, 148-154.

Optical Spectra of Schröckingerite, NaCa₃(UO₂)(SO₄)(CO₃)₃F·10H₂O

• Matkovskii AO, Platonov AN, Tarashchan AN (1983) Optical absorption spectra and color of uranyl-containing minerals. Mineralogicheskii Sbornik (Lvov) 37, 7-19. (In Russian)

Optical Spectra of Sepiolite, Mg₄(Si₆O₁₅)(OH)₂·6H₂O 

• Babu KS, Sudhana BM, Vedananda S, Reddy BJ (1995) Spectral studies of Ni(II) in sepiolite mineral. Indian Mineralogist 29, 18-22.

Optical Spectra of Serandite, NaMn₂Si₃O₈(OH) 

• Manning PG (1968) Absorption spectra of the manganese-bearing chain silicates pyroxmanganite, rhodonite, bustamite and serandite. Canadian Mineralogist 9, 348-357.
• Chanmuang CN, Škoda R, Zoysa EG 2021 Spectroscopic Study of Serendibite from Sri Lanka. The Journal of Gemmology  37, 451-454.

Optical Spectra of Serpentines, Mg₃[Si₂O₅](OH)₄ 

• Reddy BJ, Sarma KBN (1982) Electronic absorption spectrum of chrysotile asbestos. Indian Journal of Physics, B 56B, 29-34.    
• Platonov AN, Langer K. Wievióra A, Andrut M (1995) Electronic absorption spectra of chromium-bearing amesite. European Journal of Mineralogy 7, 961-965.
• Reddy SN, Ravikumar RVSSN, Reddy BJ, Reddy YP, Rao PS, (2001) Spectroscopic investigations on Fe³⁺, Fe²⁺ and Mn²⁺ bearing antigorite mineral. Neues Jahrbuch fuer Mineralogie, Monatshefte (2001), (6), 261-270. 
• Rossman GR, Laurs BM (2014) Orange lizardite from South Africa. The Journal of Gemmology 34, 98-99.

Optical Spectra of Shattuckite, Cu₅(Si₂O₆)₂(OH)₂ 

• Sarma KBN, Reddy BJ, Lakshman SVJ (1982) Absorption spectra of copper(2+) in shattuckite and plancheite. Physics Letters A, 92A, 305-308.
• Sarma KBN, Reddy BJ, Lakshman SVJ (1984) EPR and optical spectra of certain copper-​bearing minerals:  a tool to probe site symmetry of copper(II) ion. Proceedings of the Nuclear Physics and Solid State Physics Symposium (1984),  25, 209-210. 

Optical Spectra of Sinhalite, MgAl(BO4) 

• Farrell EF, Newnham RE  (1965) Crystal-​field spectra of chrysoberyl, alexandrite, peridot, and sinhalite. American Mineralogist 50, 1972-1981.  

Optical Spectra of Smirnite, Bi₂TeO₅ 

• Frost RL, Reddy BJ, Keeffe EC (2010) An application of near-infrared and mid-infrared spectroscopy to the study of selected minerals. Radiation Effects and Defects in Solids, 165, 193-205.

Optical Spectra of Sogdianite, KZr₂Li₃[Si₁₂O₃₀]

• Kaneva E, Belozerova O, Radomskaya T, Shendrik R (2024) Crystal chemistry, Raman and FTIR spectroscopy, optical absorption, and luminescence study of Fe-dominant sogdianite. Zeitschrift fur Kristallographie-Crystalline Materials. DOI10.1515/zkri-2023-0055
  

Optical Spectra of Sphaerocobaltite, CoCO₃

• Frost RL, REddy BJ, Wain DL, Hales MC (2006) An application of near-infrared spectroscopy to the study of carbonate minerals - smithsonite, rhodochrosite, sphaerocobaltite and cadmium smithsonite. Journal of Near Infrared Spectroscopy 14, 317-324.    

Optical Spectra of Stichtite, Mg₆Cr₂(OH)₁₆[CO₃]·4H₂O 

• Reddy KM, Moorthy LR, Reddy BJ (1985) Absorption spectrum of chromium(3+) in stichtite mineral. Indian Journal of Physics, A 59A, 379-82. 

Optical Spectra of Stringhamite, CaCu(SiO₄)·H₂O 

• Vedanand S, Reddy BJ, Reddy YP (1991)  Spectroscopic investigations on stringhamite, Ca[Cu(SiO₄)​]​(H₂O). Solid State Communications 77, 231-234.

Optical Spectra of Sulfo Salts

• Platonov AN, Mozgova NN (1974) Effect of crystal-chemical features on the forbidden band gap energy of complex sulfides (sulfo salts). Izvestiya Akademii Nauk SSSR, Seriya Geologicheskaya (1974), (2), 71-79. (In Russian)

Optical Spectra of Sussexite, MnBO₂(OH)

• Keester KL, White WB (1966) Crystal field spectra and chemical bonding in manganese minerals. In: Papers and proceedings of the fifth general meeting, International Mineralogical Association. Cambridge, England, Aug 30-Sep 3, 1066. p22-35.

Optical Spectra of Suzukiite, BaVOSi₂O₆

• Kato K, Sugitani Y, Nagashim K (1974) Absorption spectrum of a new barium vanadyl silicate BaVOSi₂O₆. Mineralogical Journal 7, 421-430.

Optical Spectra of Taaffeites, BeMg₃Al₈O₁₆

• Scarratt K (1986) Notes from the Laboratory - 7. Journal of Gemmology 20, 145-153.
• Leelawatanasuk T, Atichat W, Sun TT, Sriprasert B, Jakkawanvibul J (2014) Some characteristics of taaffeite from Myanmar. The Journal of Gemmology 34, 144-148.

Optical Spectra of Takovite, Ni₆Al₂(OH)₁₆[CO₃]·4H₂O

• Sarma KBN, Reddy BJ, Lakshman SVJ (1983) Absorption spectra of nickel(2+) in zaratite and takovite. Physica Scripta 28, 125-8. 
• Frost RL, Keeffe EC, Reddy BJ (2010) Characterisation of Ni carbonate-bearing minerals by UV-Vis-NIR spectroscopy. Transition Metal Chemistry 35, 279-287.

Optical Spectra of Talc, Mg₃Si₄O₁₀(OH)₂

• Vedanand S, Rao PS, Reddy BJ (1993)Spectroscopic investigations on different grade samples of talc. Radiation Effects and Defects in Solids 127, 169-176.

Optical Spectra of "Tawmanite', Cr-rich epidote

• Burns RG (1970) Mineralogical Applications of Crystal Field Theory. Cambridge University Press, 1970, p67.

Optical Spectra of Teineite, Cu(TeO₃)·2H₂O

• Frost RL, Reddy BJ, Keeffe EC (2010) An application of near-infrared and mid-infrared spectroscopy to the study of selected minerals. Radiation Effects and Defects in Solids, 165, 193-205. 

Optical Spectra of Tennantite, Cu₁₂As₄S₁₃ 

• Reddy SL, Fayazuddiin M, Reddy NCG, Endo T, Frost RL (2008) Electron paramagnetic resonance and optical absorption spectral studies on tetrahedrite and tennantite minerals. Radiation Effects and Defects in Solids 163, 19-27.       

Optical Spectra of Tenorite

• Reddy RRS, Reddy SL, Rao PS, Frost RL (2010) Optical absorption and EPR studies on tenorite mineral. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 75, 28-31.

Optical Spectra of Tephroite, Mn₂SiO₄       

• Keester KL, White WB (1968) Crystal field spectra and chemical bonding in manganese minerals. In: Papers and proceedings of the fifth general meeting, International Mineralogical Association. Cambridge, England, Aug 30-Sep 3, 1966. p22-35.
• Burns RG (1970a) Mineralogical Applications of Crystal Field Theory. Cambridge University Press, Cambridge.
• Platonov AN (1976) The nature of colour in minerals. Kiev, Naukova Dumka (In Russian).
• Stidham HD, Bates JB, Finch CB (1976) Vibrational spectra of synthetic single crystal tephroite, Mn₂SiO₄. Journal of Physical Chemistry 80, 1226-1234.  
• Hålenius U, Bosi F, Skogby H (2007) Galaxite, MnAl₂O₄, a spectroscopic standard for tetrahedrally coordinated Mn²⁺ in oxygen-based mineral structures. American Mineralogist 92, 1225-1231     
• Jyršl J (2018) Colour-change tephroite from South Africa. The Journal of Gemmology 36, 292.
  

Optical Spectra of Tetrahedrite, Cu₆(Cu₄Fe₂)Sb₄S₁₂S

• Reddy SL, Fayazuddiin M, Reddy NCG, Endo T, Frost RL (2008) Electron paramagnetic resonance and optical absorption spectral studies on tetrahedrite and tennantite minerals. Radiation Effects and Defects in Solids 163, 19-27.       

Optical Spectra of Thalenite-(Y), Y₃Si₃O₁₀F

• Krasil'shchikova OA, Platonov AN, Povarennykh AS (1975) Optical absorption spectrum of erbium(3+) in thalenite. Dopovidi Akademii Nauk Ukrains'koi RSR, Seriya B:  Geologiya, Geofizika, Khimiya ta Biologiya (1975), (12), 1079-1080. (In Ukranian)

Optical Spectra of Tlapallite, H₆(Ca,Pb)₂(Cu,Zn)₃O₂(SO₄)(Te⁴⁺O₃)₄(Te⁶⁺O₄)

• Frost RL, Keeffe EC, Reddy BJ (2009) An application of near-infrared and midinfrared spectroscopy to the study of selected tellurite minerals: xocomecatlite, tlapallite and rodalquilarite. Transition Metal Chemistry, 34, 23-32.

Optical Spectra of Tornebohmite, (Ce,La)₂Al(SiO₄)₂(OH)

• Platonov AN, Krasilshchikova OA, Tarashchan AN (1975) Optical absorption of rare earth ions in minerals. Konstitutsiya i Svoistva Mineralov 9, 58-64. (In Russian)

Optical Spectra of Triplite, Mn₂PO₄F 

• Grum-Grzhimailo SV (1962) Absorption spectra of Mn(II)​-​containing minerals. Zapiski Vserossiiskogo Mineralogicheskogo Obshchestva 91, 86-9. (In Russian)
• Lu Y, Pei JC, Gao YT, Chen BY (2022) Chemical Constituents and Spectra Characterization of Gem-Grade Triplite. Spectroscopy and Spectral Analysis 42, 1204-1208 (in Chinese). Doi:10.3964/j.issn.1000-0593(2022)04-1204-05
• Qu Z , Li P, Liu P, Zhao B  (2022) Gemmological and Spectral Characteristics of Triplite from Pakistan. Journal of Gems & Gemmology 24, 125-133, (in Chinese). doi: 10.15964/j.cnki.027jgg.2022.05.012 
  

Optical Spectra of Turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O

• Nikolskaya LV, Lisitsyna EE, Samoilovich MI (1974) Coloration of turquoise from the deposits of Central Asia. Izvestiya Akademii Nauk SSSR, Seriya Geologicheskaya 1974, 105-11. (In Russian )
• Zhang H.F., Lin C.Y., Ma Z.W., Yang Z.G. (1982) Magnetic properties, characteristic spectra and colour of turquoise. Acta Mineralogica Sinica 4, 254–261 [(In Chinese)]. 
• Lin C, Zhang H, Yang Z (1983) Ligand-​field theory study on the optical absorption spectrum and magnetic properties of copper(2+) in turquoise. Fenzi Kexue Yu Huaxue Yanjiu 3, 77-83. (In Chinese)  
• Sarma KBN, Reddy BJ, Lakshman SVJ (1984) EPR and optical spectra of certain copper-​bearing minerals:  a tool to probe site symmetry of copper(II) ion. Proceedings of the Nuclear Physics and Solid State Physics Symposium 25, 209-210.  
• Sarma KBN, Moorthy LR, Reddy BJ, Vedanand S (1988) EPR and electronic absorption spectra of copper-​bearing turquoise mineral. Physics Letters A 132, 293-297.  
• Luan L.J., Han Z.X., Wang C.Y., Zhang Y.W. (2004) Elementary research on color-forming mechanism of turquoise. Northwestern Geology 37, 77–82 [(In Chinese)].
• Xiong Y, Chen Q (2008) Visible absorption spectrum characteristics of Qingu turquoise from Hubei province. Baoshi He Baoshixue Zazhi 10, 34-37. (In Chinese)  
• Zhang BF, Lin JZ (2015) Theoretical studies of the EPR g factors and optical spectra of copper bearing turquoise mineral. Chemica Sinica 6, 30-33. 
• Liu L, Yang M, Li Y (2020) Unique raindrop pattern of turquoise from Hubei, China. Gems & Gemology 56, 380-400.
• Wang X, Ying G (2021) The impact of trace metal coations and absorbed water on colour transition of turquoise. Royal Society Open Science 8, 201110.
• Wu Y, Chen Q, Li Y, Cao M, Yin Z, Wang H, Liu X (2022) Gemmological Characteristics of Turquoise from Hami, Xinjiang, China. The Journal of Gemmology 38, 254-270.
• Zhang Y, Yang M, Liu L, Wen H, Shirdam B, Shen AH (2023). Mineralogical and Spectral Characteristics of Turquoise and Associated Minerals from Baghu, Iran. Journal of Gems & Gemmology 25, 43-53. DOI: 10.15964/j.cnki.027jgg.2023.03.006
  

Optical Spectra of Tyuyamunite, Ca(UO₂)₂(VO₄)₂·5-8H₂O

• Platonov AN, Tarashchan AN, Povarennykh AS (1972) Optical spectroscopy of vanadium in natural minerals.  II.  Optical absorption spectra of vanadates with complex radicals. Konstitutsiya i Svoistva Mineralov 6, 58-62. (In Russian)

Optical Spectra of Ullmannite, NiSbS

• Reddy SN, Ravikumar RVSSN, Reddy BJ, Reddy YP (2000) Chemical and electronic spectral studies of ullmannite (Ni₄Sb₄S₄). Indian Journal of Engineering & Materials Sciences 7, 459-460.

Optical Spectra of Uranyl Minerals, UO₂²⁺

• Platonov AN, Povarennykh AS, Tarashchan AN, Bondar VV (1972) Color of uranyl-bearing minerals. Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva 101, 423-8. (In Russian)
• Platonov AN, Povarennykh AS, Tarashchan AN, Bondar VV (1972) Effect of crystal chemical factors on the optical absorption spectra of uranyl ion in minerals. Mineralogicheskii Sbornik (Lvov) 26, 393-398. (In Russian)

Optical Spectra of Ussingite, Na₂AlSi₃O₈OH

• Belichenko VP, Novozhilov AI, Platonov AN, Povarennykh AS, Samoilovich MI (1969) The nature of ussingite color. Konstitutsiya i Svoistva Mineralov 3, 26-30. (In Russian)
• Povarennykh AS, Platonov AN, Belichenko VP (1970) On the colour of ussingite from the Ilimaussaq (South Greenland) and Lovozero (Kola Peninsula) alkaline intrusions. Bulletin of the Geological Society of Denmark 20, 20-26.
  

Optical Spectra of Voglite, Ca₂Cu(UO₂)(CO₃)₄·6H₂O

• Reddy SL, Endo T (2010) The spectroscopy of copper-​oxide-minerals. Transactions of the Materials Research Society of Japan 35, 423-429.   
• Reddy SL, Maheswaramma KS, Reddy GS, Reddy BJ, Frost RL, Endo T (2010) EPR and optical absorption spectral studies on voglite mineral. Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 77, 11-15.

Optical Spectra of Voltaite, K₂Fe²⁺₅Fe³⁺₃Al(SO₄)₁₂·18H₂O

• Beveridge D, Pay P (1979) Charge Transfer in Mixed-valence S and its Solid Solutions with Cadmium(II), solids. Part 9. Preparation, Characterization, and Optical Spectroscopy  of the Mixed-valence Mineral Voltaite [Aluminium Pentairon(II) Tri-iron(III) Dipotassium Dodecasulphate 18-Hydrate] and its Solid Solutins with Cadmium(II). Journal of the Chemical Society, Dalton 648-653.

Optical Spectra of Wakefieldite-Y, YVO₄

• Sun Z, Jin S, Gudino A, Palke AC, Akhavan AA (2023) Synthetic color-change wakefieldite. Gems & Gemology 59, 156-158.
  

Optical Spectra of Wavellite, Al₃(PO₄)₂(OH,F)₃·5H₂O 

• Foster MD, Schaller WT (1966) Cause of colors in wavellite from Dug Hill Arkansas. American Mineralogist 51, 422-428.
• Platonov AN, Tarashchan AN (1973) Optical spectroscopy of vanadium in natural minerals.  III.  Absorption spectra of vanadium(4+) and vanadium(3+) complexes. Konstitutsiya i Svoistva Mineralov 7, 75-81. (In Russian)
• Platonov AN (1976) The nature of colour in minerals. Kiev, Naukova Dumka (In Russian).
• Reddy SL, Reddy BJ, Rao PS (1993) Optical absorption and EPR spectra of oxovanadium(2+) in wavellite. Spectrochimica Acta, Part A:  Molecular and Biomolecular Spectroscopy (1993), 49A(4), 599.    
• Reddy SL, Rao PS, Reddy BH (1993) Optical absorption and EPR spectra of VO(II) in wavelite. Spectrochimica Acta A 49A, 1-18. 
• Chandrasekhar AV, Ravikumar RVSSN, Reddy BJ, Reddy YP, Rao PS (1999) Spectroscopic Investigations of Mn²⁺ in wavellite. Asian Chemistry Letters (India) 3, 30-35
• Hanson SL, Falster AU, Simmons WB (2009) Blue wavellite from the De Linde Quarry, Garland County, Arkansas. Contributed Papers in Specimen Mineralogy: Part 2. 36th Rochester Mineralogical Symposium.

Optical Spectra of Widgiemoolthalite, Ni₅(CO₃)₄(OH)₂·5H₂O

• Frost RL, Keeffe EC, Reddy BJ (2010) Characterisation of Ni carbonate-bearing minerals by UV-Vis-NIR spectroscopy. Transition Metal Chemistry 35, 279-287.
  

Optical Spectra of Wurtzite, (Zn,Fe)S

• Henn U, Schmitz F, Hyršl J (2015) Gem-quality wurtzite from Tanzania. The Journal of Gemmology 34, 669-671.
  

Optical Spectra of Xenotime, YPO₄

• Zhang N, Qu G, Wang W, Ling X (2022)  Gemmological and Spectral Characteristics of Xenotime from Pakistan. Journal of Gems & Gemmology 24, 31-34. (in Chinese).

Optical Spectra of Xocomecatlite, Cu₃(TeO₄)(OH)₄

• Frost RL, Keeffe EC, Reddy BJ (2009) An application of near-infrared and midinfrared spectroscopy to the study of selected tellurite minerals: xocomecatlite, tlapallite and rodalquilarite. Transition Metal Chemistry, 34, 23-32.

Optical Spectra of Yoderite, MgAl₃(SiO₄)₂O(OH)

• Abu-Eid RM, Langer K, Seifert F (1978) Optical absorption and Moessbauer spectra of purple and green yoderite, a kyanite-​related mineral. Physics and Chemistry of Minerals 3, 271-89. 
• Langer K, Smith G, Halenius U (1982) Reassignment of the absorption spectra of purple yoderite. Physics and Chemistry of Minerals 8, 143-5.

Optical Spectra of Zaratite, Ni₃(CO₃)(OH)₄·4H₂O

• Sarma KBN, Reddy BJ, Lakshman SVJ (1983) Absorption spectra of nickel(2+) in zaratite and takovite. Physica Scripta 28, 125-128. 
• Frost RL, Keeffe EC, Reddy BJ (2010) Characterisation of Ni carbonate-bearing minerals by UV-Vis-NIR spectroscopy. Transition Metal Chemistry 35, 279-287.

Optical Spectra of Zincite, ZnO

• Gevorkyan SV, Platonov M, Povarennikh OS (1968)  Optical absorption spectrum of zincite. Dopovidi Akademii Nauk Ukrainskoi RSR, Seriya B:  Geologiya, Geofizika, Khimiya ta Biologiya 30, 62-5. (In Ukranian) 
• Zhang J, Gao Y, Shi Guanghai (2017) Characteristics of gem-quality by-product synthetic zincite. Gems & Gemology 53, 82-89.