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
(15 K) with lower contents of Fe2+ but becomes brown
(6 K) at high iron contents .
Images of representative olivines
-
Forsterite 418 image; GRR
418, Green forsterite crystal from a basalt flow, San Carlos, Arizona,
1.14 mm thick. Data files: alpha, beta,gamma;
-
Fayalite 1582 image; 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 image, GRR 236,
blue-lavender tephroite crystal from Franklin, New Jersey, 0.282 mm thick.
Data files: alpha; beta;
- Monticellite 182 image, 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..
High Pressure phases in the (Mg,Fe)2SiO4 family
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