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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[]

  1. 1,00 1,01 1,02 1,03 1,04 1,05 1,06 1,07 1,08 1,09 1,10 1,11 1,12 1,13 1,14 1,15 1,16 Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6
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