Corkite

Short description: Phosphate mineral

Corkite

Corkite on a goethite matrix

General
Category| Phosphate minerals
Formula
(repeating unit)| PbFe3[(OH)6:SO4:PO4]
Strunz classification| 8.BL.05
Dana classification| 43.4.1.2
Crystal system| Trigonal
Crystal class| Ditrigonal pyramidal (3/m)
(same H-M symbol)
Space group| R3m
Unit cell| a = 7.3065(5) Å,
c = 16.897(2) Å;
V = 781.2 Å³; Z = 3
Identification
Formula mass| 667.82 g/mol
Color| Brown to light yellowish brown, pale yellow, yellowish green to dark green
Crystal habit| Crystals pseudocubic rhombohedral with prominent {1011}. Commonly in crusts and massive
Cleavage| Perfect on {0001}
Mohs scale hardness| 3.5–4.5
|re|er}}| Vitreous, resinous
Diaphaneity| transparent
Specific gravity| 4.295 (measured), 4.31 (calculated)
Optical properties| Uniaxial (−), may appear anomalously biaxial
Refractive index| nω = 1.930 nε = 1.930 n = 1.93 – 1.96
Birefringence| δ = 0.000
Other characteristics| Readily soluble in warm HCl
References| [1][2][3][4][5]

Corkite is a phosphate mineral in the beudantite subgroup of the alunite group. Corkite is the phosphate analogue of beudantite and with it, a complete solid solution range exists. Corkite will also form a solid solution with kintoreite.

Corkite is named after County Cork, Ireland; the location where the first notable amount was discovered in 1869.[2] Like many of the other minerals in the beudantite group, corkite is a relatively uncommon, secondary mineral that occurs in oxidation zones near hydrothermal base metal deposits.[2] It occurs associated with pyromorphite, malachite, plumbojarosite, limonite and quartz.[5]

## References

1. ↑ Mineralienatlas
2. ↑ 2.0 2.1 2.2 Mindat.org http://www.mindat.org/min-1130.html
3. ↑ Webmineral.com http://webmineral.com/data/Corkite.shtml
4. ↑ EuroMin.net http://euromin.w3sites.net//mineraux/CORKITE.html
5. ↑ 5.0 5.1 "Handbook of Mineralogy". http://www.handbookofmineralogy.com/pdfs/corkite.pdf.
6. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode: 2021MinM...85..291W.

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