Vanadiocarpholite

Vanadiocarpholite (Mn+2V+3AlSi2O6(OH)4) is straw yellow to brown silicate mineral. It crystallizes in the orthorhombic crystal system. It is the vanadium rich variety of carpholite (Mn+2Al2Si2O6(OH)4).

Vanadiocarpholite
General
CategorySilicate mineral
Formula
(repeating unit)
Mn+2V+3AlSi2O6(OH)4
IMA symbolVcar[1]
Strunz classification9.DB.05
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupCcca
Unit cella = 13.83 Å, b = 20.681 Å
c = 5.188 Å; Z = 8
Identification
ColorPale-straw yellow, honey-yellow to brown
Crystal habitPrismatic to acicular crystal clusters, vein fillings
CleavagePerfect on {010}
TenacityFlexible
LusterVitreous, silky
DiaphaneityTransparent
Optical propertiesBiaxial (+)
Refractive indexnα=1.684, nβ=1.691, nγ=1.7
Birefringence0.0160
References[2][3]

Discovery and occurrence

It was first described in 2005 for an occurrence in the Molinello Mine, Graveglia Valley, Genova Province, Liguria, Italy.[3] It occurs in chert in a manganese ore deposit as vein fillings in silicified wood.[2]

Chemical composition

It consists of:[2]

Manganese 15.56% Mn 20.09% MnO
Aluminium 7.64% Al 14.44% Al2O3
Vanadium 14.43% V 21.23% V2O3
Silicon 15.91% Si 34.04% SiO2
Hydrogen 1.14% H 10.21% H2O
Oxygen 45.32% O

References


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