Vanadiocarpholite

Vanadiocarpholite
General
Category	Silicate mineral
Formula (repeating unit)	Mn2+V3+AlSi2O6(OH)4
IMA symbol	Vcar [1]
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	[2] [3]

Vanadiocarpholite (Mn²⁺V³⁺AlSi₂O₆(OH)₄) is straw yellow to brown silicate mineral. It crystallizes in the orthorhombic crystal system. It is the vanadium rich variety of carpholite (Mn²⁺Al₂Si₂O₆(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

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. Vanadiocarpholite data on Webmineral.com
3. Vanadiocarpholite on Mindat.org