Challacolloite
Challacolloite, KPb2Cl5, is a rare halide mineral. It crystallizes in the monoclinic system (with space group P21/c[1]) and occurs as white fumarolic encrustations on lava. It occurs as intergrowths with cotunnite.[2]
 Honey yellow Challacolloite crystals from the famous locality of La Fossa Crater (Vulcano Island, Aeolian Islands, Sicily, Italy) | |
| General | |
|---|---|
| Category | Mineral |
| Formula (repeating unit) | KPb2Cl5 |
| 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) |
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 Kudryavyi volcano in the Kuriles and also from the Satsuma-Iwojima volcano in Japan.[3] It was recognized as a valid mineral species by the IMA (International Mineralogical Association) in 2005.[3]
External links
- 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. doi:10.1007/s00710-008-0041-2.
- Webmineral
- Mindat 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
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