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]
| Chrysothallite | |
|---|---|
| General | |
| Category | Halide mineral |
| Formula (repeating unit) | 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] |
Notes on chemistry
editChrysothallite contains a relative high amount of zinc admixture. Zinc is substituting for copper.[3]
Association and origin
editChrysothallite 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
Crystal structure
editThe crystal structure of chrysothallite is unique. Its building elements are:[3]
- 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
editChrysothallite 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
edit- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Mineralienatlas
- ^ a b c d e f g 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
- ^ a b "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.
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