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
Category	Silicate mineral
Formula (repeating unit)	Mn+2V+3AlSi2O6(OH)4
Strunz classification	9.DB.05
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Space group	Ccca
Unit cell	a = 13.83 Å, b = 20.681 Å c = 5.188 Å; Z = 8
Identification
Color	Pale-straw yellow, honey-yellow to brown
Crystal habit	Prismatic to acicular crystal clusters, vein fillings
Cleavage	Perfect on {010}
Tenacity	Flexible
Luster	Vitreous, silky
Diaphaneity	Transparent
Optical properties	Biaxial (+)
Refractive index	nα=1.684, nβ=1.691, nγ=1.7
Birefringence	0.0160
References	[1][2]

Discovery and occurrenceEdit

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

Chemical compositionEdit

It consists of:

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

This article uses material from the Wikipedia article  Metasyntactic variable, which is released under the  Creative Commons Attribution-ShareAlike 3.0 Unported License.