The tetravalent manganese oxides: identification, hydration, and structural relationships
by infrared spectroscopy
Russel M. Potter and
George R. Rossman
Division of Geological and Planetary
Sciences
California Institute of Technoogy
Pasadena, CA 91125
Abstract
A compilation of the infrared powder absorption spectra of most
naturally occurring tetravalent and trivalent manganese oxides is
presented which is intended to serve as a basis for the spectroscopic
identification of these minerals in both ordered and disordered
varieties, including those too disordered for X-ray diffraction
studies. A variety of synthetic manganese oxides are also included for
comparison to the natural phases. The samples include: aurorite,
birnessite, braunite, buserite, chalcophanite, coronadite,
cryptomelane, groutite, hausmannite, hollandite, lithiophorite,
manganite, manganese(III) manganate(IV), manganosite, manjiroite,
marokite, nsutite, partridgeite, pyrolusite, quenselite, rancieite,
ramsdellite, ro manechite, sodium manganese(II,III) manganate(IV),
todorokite, and woodruffite. The spectra indicate that well-ordered
water occurs in ramsdellite, chalcophanite, and most ro manechites.
Disordered water is observed in the spectra of nsutite, hollandites,
birnessite, to dorokite, buserite, and rancieite. The infrared spectra
of well-ordered todorokite, birnessite and rancieite differ which
indicates that they possess different structures and should be re
garded as distinct mineral species. Much variation is observed in the
spectra of pyrolusites, nsutites, birnessites, and todorokites which is
interpreted as arising from structural disorder. Spectral trends
suggest that todorokite, birnessite and rancieite have layered
structures.
last updated: 5-Oct-2020