- Corkite
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Corkite General Category Phosphate minerals Chemical formula PbFe3[(OH)6:SO4:PO4] Strunz classification 08.BL.05 Dana classification 43.4.1.2 Crystal symmetry Trigonal hemimorphic (3 2/m) Unit cell a = 7.3065(5) Å, c = 16.897(2) Å; V 781.2 ų; Z = 3 Identification Molar mass 667.82 g 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 Crystal system Trigonal Cleavage Perfect on {0001} Mohs scale hardness 3.5 - 4.5 Luster 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] 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.[1] 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.[1] It occurs associated with pyromorphite, malachite, plumbojarosite, limonite and quartz.[4]
References
- ^ a b c Mindat.org http://www.mindat.org/min-1130.html
- ^ Webmineral.com http://webmineral.com/data/Corkite.shtml
- ^ EuroMin.net http://euromin.w3sites.net//mineraux/CORKITE.html
- ^ a b Handbook of Mineralogy
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