Thomsenolite is a mineral with formula: NaCaAlF6·H2O. It is an alteration product of cryolite.[1]
| Thomsenolite |
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 Thomsenolite (obelisks) and some pseudocubic ralstonite (picture center) |
| General |
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| Category | Halide minerals |
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Formula
(repeating unit) | NaCaAlF6·H2O |
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| Strunz classification | 3.CB.40 |
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| Crystal system | Monoclinic |
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| Crystal class | Prismatic (2/m)
(same H-M symbol) |
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| Space group | P21/b |
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| Identification |
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| Color | Colourless, white, pale lilac; brownish or reddish tinted due to staining; colourless in transmitted light. |
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| Cleavage | Perfect
On {001}; {110} distinct. |
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| Fracture | Irregular/ uneven |
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| Tenacity | Brittle |
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| Mohs scale hardness | 2 |
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| Lustre | Vitreous, pearly |
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| Streak | White |
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| Diaphaneity | Transparent, translucent |
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| Density | 2.981 g/cm3 |
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It was discovered in 1868 in Ivigtut, Greenland and named for Hans Peter Jorgen Julius Thomsen (1826–1909).