Challacolloite
| Challacolloite | |
|---|---|
 Honey yellow Challacolloite crystals from the famous locality of La Fossa Crater (Vulcano Island, Aeolian Islands, Sicily, Italy) | |
| General | |
| Category | Minerals |
| Formula | KPb2Cl5 |
| IMA symbol | Chc[1] |
| Strunz classification | 3.AA.55 (10th) |
| Dana classification | 11.4.2.1 |
| Crystal system | Monoclinic |
| Crystal class | 2/m - Prismatic |
| Unit cell | 878.2 ų |
| Identification | |
| Formula mass | 630.83 gm |
| Colour | Colourless to white |
| Crystal habit | Aggregate |
| Fracture | Brittle, subconchoidal fragments |
| Mohs scale hardness | 2-3 |
| Luster | Adamantine/Greasy |
| Streak | White |
| Specific gravity | 4.77 (Calculated) |
| Density | 4.77 g/cm3 (Calculated) |
| Optical properties | Biaxial (+), a=2.004, b=2.01, g=2.024, bire=0.0200 |
| Refractive index | nα = 2.004 nβ = 2.010 nγ = 2.024 |
| 2V angle | 67° (calculated) |
Challacolloite, KPb2Cl5, is a rare halide mineral. It crystallizes in the monoclinic system (with space group P21/c[2]) and occurs as white fumarolic encrustations on lava. It occurs as intergrowths with cotunnite.[3]
It was first described from a finding at the Challacollo Mine, Iquique, Chile and thereafter identified in specimens from the 1855 Mount Vesuvius eruption and from the Kudryavyivolcano in the Kuriles and also from the Satsuma-Iwojima volcano in Japan.[4] It was recognized as a valid mineral species by the IMA (International Mineralogical Association) in 2005.[4]
Artificially grown KPb2Cl5 crystals are used for lasers.[5]
External links
- ^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.
- ^Mitolo, D.; Pinto, D.; Garavelli, A.; Bindi, L.; Vurro, F. (May 2009). "The role of the minor substitutions in the crystal structure of natural challacolloite, KPb2Cl5, and hephaistosite, TlPb2Cl5, from Vulcano (Aeolian Archipelago, Italy)". Mineralogy and Petrology. 96 (1–2): 121–128. Bibcode:2009MinPe..96..121M. doi:10.1007/s00710-008-0041-2. S2CID 128797167.
- ^Webmineral
- ^ abMindat with location data
- ^Jochen Schlüter, Dieter Pohl and Sergey Britvin; The new mineral challacolloite, KPb2Cl5, the natural occurrence of a technically known laser material, N. Jb. Miner. Abh., 2005, Vol.182/1, p. 95–101 pdf
