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;
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
to the list of minerals
to the Mineral Spectroscopy home page