Vanadiocarpholite

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Vanadiocarpholite
General
Category
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]

Vanadiocarpholite (Mn+2V+3AlSi2O6(OH)4) is straw yellow to brown

orthorhombic crystal system. It is the vanadium rich variety of carpholite
(Mn+2Al2Si2O6(OH)4).

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