Vauquelinite

Vauquelinite
General
CategoryPhosphate mineral
Formula
(repeating unit)		CuPb2(CrO4)(PO4)(OH)
IMA symbolVql[1]
Strunz classification7.FC.05
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/n
Unit cella = 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 habitIrregular wedge shaped crystals, mammillary, reniform masses
TwinningPresent on {102}
CleavageIndistinct
FractureIrregular
TenacityBrittle
Mohs scale hardness2.5 – 3
LusterAdamantine, resinous
StreakGreenish or brownish
DiaphaneityTranslucent
Specific gravity6.16
Optical propertiesBiaxial (−)
Refractive indexnα = 2.110 nβ = 2.220 nγ = 2.220
Birefringenceδ = 0.110
PleochroismX = Light green, Y = Light brown, Z = Light brown
2V angleNear zero
References[2][3][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

  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. ^ a b c Mindat – Vauquelinite
  3. ^ Webmineral – Vauquelinite
  4. ^ a b Handbook of Mineralogy – Vauquelinite


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