Olivine Group Visible Spectra (generally 350 - 2000 nm)
Olivine derives its color primarily from Fe2+
content. The basic
color is modified by minor amounts of Fe3+, Ti4+,
and Ni2+. It is green with
lower contents of Fe2+ but becomes brown at high iron
contents .
Images of representative olivine spectra
- Forsterite
418; GRR
418, Green forsterite crystal from a basalt flow, San Carlos, Arizona,
1.14 mm thick. Data files: alpha,
beta, gamma;
- Forsterite
3238, GRR 3238, a 'mint'
green forsterite from Supat, Pakistan
- Forsterite LUNA
24, Forsterite from Earth's moon. Plotted as 0.040 mm thick.
- Fayalite
1582; GRR 1582,
Brown fayalite crystal from a gas cavity in an obsidian flow, Coso
Mountains,
Kern County, California, 0.025 mm thick. Data files: alpha; beta;
gamma;
- Tephroite
236, GRR 236,
blue-lavender tephroite crystal from Franklin, New Jersey, 0.282 mm
thick.
Data files: alpha; beta;
- Monticellite 182,
GRR 182, off-white crystal from Magnet Cove, Arkansas, USA,
plotted as 1.0 mm thick. Data files: alpha , beta, gamma;
Synthetic olivines with different transition metal ions
Orientation convention relating the cyrstallographic axes to the
directions
of the optical absorption spectra: 10 Ångstrom axis =
alpha;
6 Ångstrom axis = beta; 4.7 Ångstrom axis = gamma.
Spectra at liquid nitrogen temperature (78 K) generally show better
resolution
of many of the spectroscopic features.
Synthetic olivines doped with cobalt.
Synthetic olivines doped with nickel.
Two synthetic olivines doped with chromium.
Nominally they contain Cr3+ but the spectra
suggest that multiple oxidations states are present.
High Pressure phases in the (Mg,Fe)2SiO4
family
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