Vauquelinite

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Vauquelinite
Vauquelinite-120513.jpg
General
Category Phosphate mineral
Formula 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
ColorOlive-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 hardness2.5 – 3
Luster Adamantine, resinous
Streak Greenish or brownish
Diaphaneity Translucent
Specific gravity 6.16
Optical propertiesBiaxial (−)
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]

Vauquelinite is a complex mineral with the formula Cu Pb 2(Cr O 4)(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

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 3 Mindat – Vauquelinite
  3. Webmineral – Vauquelinite
  4. 1 2 "Handbook of Mineralogy – Vauquelinite" (PDF). Archived from the original (PDF) on 2016-03-03. Retrieved 2013-01-25.