| Hydrogrossular | |
 |
|
| General | |
|---|---|
| Category | Mineral Series |
| Chemical formula | Ca3Al2(SiO4)3-x(OH)4x |
| Identification | |
| Color | green to bluish green, pink, white, gray [1] |
| Crystal habit | Massive |
| Crystal system | cubic [1] |
| Cleavage | none |
| Fracture | conchoidal [1] |
| Mohs Scale hardness | 7 - 7.5 [1] |
| Luster | vitreous |
| Specific gravity | 4.15 (+.05, -.03)[1] |
| Polish luster | vitreous to subadamantine [1] |
| Optical properties | Single refractive, anomalous aggregate reaction [1] |
| Refractive index | 1.810 (+.004, -.020) |
| Birefringence | none |
| Pleochroism | none |
| Ultraviolet fluorescence | inert [1] |
| Absorption spectra | dark green hydrogrossular often shows cutoff below 460nm. Other color stones may show line around 463nm, indicating some idocrase content[1] |
Hydrogrossular, is a calcium aluminium garnet series between the species Grossular and Hibschite Ca3Al2(SiO4)3-x(OH)4x, with hydroxide (OH) partially replacing silica (SiO4).[1] Hydrogrossular is found in massive crystal habit, sometimes grown in with idocrase. [1]
Hydrogrossular is translucent to opaque, and found in green to bluish green, pink, white, and gray.[1] The cause of the green color is chromium, and possibly iron.[1] Pink hydrogrossular is caused by the presence of manganese.[1] Hydrogrossular may have dark gray to black small inclusions. [1]It has similarites to jade, and has the misnomers Transvaal jade, and African jade.[1]
Hydrogrossular is sometimes used as a gemstone, being cabochon cut, or made into beads. Sources for green and pink hydrogrossular are South Africa, Canada, and the US. White hydrogrossular is sourced from Burma and China.[1]
External links
References
- ^ a b c d e f g h i j k l m n o p q Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6
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