Chrysothallite
| Chrysothallite | |
|---|---|
| General | |
| Category | Halide mineral |
| Formula (repeating unit) | K6Cu6Tl3+Cl17(OH)4•H2O |
| Crystal system | Tetragonal, I4/mmm |
| Space group | Tetragonal - Ditetragonal Dipyramidal (4/mmm) |
| Unit cell | a=11.37, b=26.21 (approximated) |
| 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 | [1][2] |
Chrysothallite is a rare thallium-bearing chloride mineral with the formula K6Cu6Tl3+Cl17(OH)4•H2O.[1][2] Chrysothallite is unique in being only the second mineral with essential trivalent thallium,[1] a feature shared with natural thallium(III) oxide, avicennite.[3] Another examples of natural thallium chlorides are steropesite, Tl3BiCl6, and lafossaite, TlCl.[4][5] Chrysothallite is one of numerous fumarolic minerals discovered among fumarolic sites of the Tolbachik volcano, Kamchatka, Russia[6] The mineral is named in allusion to its colour and thallium content.[1]
Notes on chemistry
Chrysothallite contains a relative high amount of zinc admixture. Zinc is substituting for copper.[1]
Association and origin
Chrysothallite may be associated with many other minerals:[1]
- chlorides: atacamite, avdoninite, belloite, eriochalcite, mitscherlichite, sanguite, carnallite, halite, sylvite;
- sulfates: antlerite, chlorothionite, kröhnkite, natrochalcite, gypsum, kainite
Crystal structure
The crystal structure of chrysothallite is unique. Its building elements are:[1]
- layer of distorted CuCl4(OH)2 octahedra, in which the octahedra share edges
- isolated Tl-centered TlCl6 octahedra
- isolated Tl-centered TlCl4(H2O)2 octahedra
- KCl6 and KCl9 polyhedra, that connect all the above elements
Origin
Chrysothallite is supposed to be a product of interaction of relatively high-temperature fumarolic minerals with fumarolic gas and atmospheric water, that takes place in temperatures up to 150 °C (302 °F).
References
- 1 2 3 4 5 6 7 Pekov, I.V., Zubkova, N.v., Belakovskiy, D.I., Yapaskurt, V.O., Vigasina, M.F., Lykova, I.S., Sidorov, E.G., and Pushcharovsky, D.Yu., 2015. Chrysothallite K6Cu6Tl3+Cl17(OH)4.H2O, a new mineral species from the Tolbachik volcano, Kamchatka, Russia. Mineralogical Magazine 79(2), 365-376
- 1 2 "Chrysothallite: Chrysothallite mineral information and data". Mindat.org. Retrieved 2016-03-11.
- ↑ "Avicennite: Avicennite mineral information and data". Mindat.org. Retrieved 2016-03-11.
- ↑ "Steropesite: Steropesite mineral information and data". Mindat.org. Retrieved 2016-03-11.
- ↑ "Lafossaite: Lafossaite mineral information and data". Mindat.org. Retrieved 2016-03-11.
- ↑ "Tolbachik volcano, Kamchatka Oblast', Far-Eastern Region, Russia - Mindat.org". Mindat.org. Retrieved 2016-03-11.