Chrysothallite
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| Chrysothallite | |
|---|---|
| General | |
| Category | Halide mineral |
| Formula | K6Cu6Tl3+Cl17(OH)4•H2O |
| IMA symbol | Cry[1] |
| Crystal system | Tetragonal |
| Crystal class | Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) |
| Space group | I4/mmm |
| Unit cell | a = 11.37 Å, b = 26.21 Å (approximated); Z = 4 |
| Identification | |
| Color | Golden-yellow to light yellow |
| Crystal habit | tabular |
| Cleavage | None |
| Fracture | Uneven |
| Tenacity | Brittle |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent |
| Density | 2.95 (measured) |
| Optical properties | Uniaxial (+) |
| Refractive index | ω=1.72, ε=1.73 (approximated) |
| References | [2][3][4] |
Chrysothallite is a rare thallium-bearing chloride mineral with the formula K6Cu6Tl3+Cl17(OH)4•H2O.[3][4] Chrysothallite is unique in being only the second mineral with essential trivalent thallium,[3] a feature shared with natural thallium(III) oxide, avicennite.[5] Another examples of natural thallium chlorides are steropesite, Tl3BiCl6, and lafossaite, TlCl.[6][7] Chrysothallite is one of numerous fumarolic minerals discovered among fumarolic sites of the Tolbachik volcano, Kamchatka, Russia[8] The mineral is named in allusion to its colour and thallium content.[3]
Association and origin
Chrysothallite may be associated with many other minerals:[3]
- chlorides: atacamite, avdoninite, belloite, eriochalcite, mitscherlichite, sanguite, carnallite, halite, sylvite;
- sulfates: antlerite, chlorothionite, kröhnkite, natrochalcite, gypsum, kainite
