Hodgkinsonite | |
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General | |
Category | Nesosilicate |
Formula (repeating unit) | Zn2MnSiO4(OH)2 |
IMA symbol | Hgk[1] |
Strunz classification | 9.AE.20 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | P21/a |
Unit cell | a = 11.76, b = 5.31 c = 8.18 [Å]; β = 95.42°, Z = 4 |
Identification | |
Mohs scale hardness | 4+1⁄2 - 5 |
Optical properties | Biaxial (-) |
Refractive index | nα = 1.720 nβ = 1.741 nγ = 1.746 |
Birefringence | δ = 0.026 |
Dispersion | r < v moderate |
Hodgkinsonite is a rare zinc manganese silicate mineral Zn2MnSiO4(OH)2. It crystallizes in the monoclinic system and typically forms radiating to acicular prismatic crystals with variable color from pink, yellow-red to deep red. Hodgkinsonite was discovered in 1913 by H. H. Hodgkinson, for whom it is named in Franklin, New Jersey, and it is only found in that area.[2]