Vauquelinite
(repeating unit)CuPb2(CrO4)(PO4)(OH) IMA symbol Vql[1] Strunz classification 7.FC.05 Crystal system Monoclinic Crystal class Prismatic (2/m)
(same H-M symbol) Space group P21/n Unit cell a = 13.754(5) Å, b = 5.806(6) Å
c = 9.563(3) Å; β = 94.55°; Z = 4 Identification Color Olive-green, apple-green, brown to nearly black Crystal habit Irregular wedge shaped crystals, mammillary, reniform masses Twinning Present on {102} Cleavage Indistinct Fracture Irregular Tenacity Brittle Mohs scale hardness 2.5 – 3 Luster Adamantine, resinous Streak Greenish or brownish Diaphaneity Translucent Specific gravity 6.16 Optical properties Biaxial (−) Refractive index nα = 2.110 nβ = 2.220 nγ = 2.220 Birefringence δ = 0.110 Pleochroism X = Light green, Y = Light brown, Z = Light brown 2V angle Near zero References [2][3][4]
(same H-M symbol)
c = 9.563(3) Å; β = 94.55°; Z = 4
Vauquelinite is a complex mineral with the formula CuPb2(CrO4)(PO4)(OH) making it a combined chromate and phosphate of copper and lead. It forms a series with the arsenate mineral fornacite.[2]
It was first described in 1818 in the Beryozovskoye deposit, Urals, Russia, and named for Louis Vauquelin (1763–1829), a French chemist.[2] It occurs in oxidized hydrothermal ore deposits and is associated with crocoite, pyromorphite, mimetite, cerussite, beudantite and duftite at the type locality in Russia.[4]
References
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