corkite

{{Infobox mineral | name = Corkite | category = Phosphate minerals | boxwidth = 24 | boxbgcolor = | image = Corkite-Goethite.jpg | caption = Corkite on a goethite matrix | formula = PbFe3[(OH)6:SO4:PO4] | IMAsymbol = Cok | molweight = 667.82 g/mol | strunz = 8.BL.05 | dana = 43.4.1.2 | system = Trigonal | class = Ditrigonal pyramidal (3/m) (same H-M symbol) | symmetry = R3m | unit cell = a = 7.3065(5) Å, c = 16.897(2) Å; V = 781.2 Å³; Z = 3 | color = Brown to light yellowish brown, pale yellow, yellowish green to dark green | habit = Crystals pseudocubic rhombohedral with prominent {101}. Commonly in crusts and massive | lattice = | twinning = | cleavage = Perfect on {0001} | fracture = | tenacity = | mohs = 3.5–4.5 | luster = Vitreous, resinous | refractive = nω = 1.930 nε = 1.930 n = 1.93 – 1.96 | opticalprop = Uniaxial (−), may appear anomalously biaxial | birefringence = δ = 0.000 | pleochroism = | 2V = | dispersion = | streak = | gravity = 4.295 (measured), 4.31 (calculated) | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = transparent | other = Readily soluble in warm HCl |references = }}

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.