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Cafarsite

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Cafarsite
Cafarsite on granite
General
CategoryArsenites
Formula
(repeating unit)
Ca
8
(Ti,Fe2+
,Fe3+
,Mn)
6–7
(AsO
3
)
12
·4H
2
O
IMA symbolCaf[1]
Strunz classification4.JC.05
Crystal systemIsometric
Crystal classDiploidal (m3)
H–M Symbol (2/m 3)
Space groupPn3
Unit cella = 15.984 Å; Z = 4
Identification
Formula mass2,230.31 g/mol
ColorDark brown
Crystal habitCubic/octahedral crystals
FractureConchoidal
Mohs scale hardness5+12 - 6
Lustersub-metallic
StreakYellow brown
DiaphaneityTranslucent to opaque
Specific gravity3.9
Optical propertiesIsotropic
Refractive indexn = 2.2
References[2][3][4]

Cafarsite (Ca
8
(Ti,Fe2+
,Fe3+
,Mn)
6–7
(AsO
3
)
12
·4H
2
O
) is a rare calcium iron arsenite mineral. Manganese and titanium occur with iron in the formula.

It was first described in 1966 for an occurrence in the Binn Valley, Valais, Switzerland. Its name is from the composition, calcium, ferrum (iron), and arsenic.[3][2][4] It has also been reported from Piedmont, Italy and the Hemlo gold mine in the Thunder Bay District, Ontario, Canada.[4][3]

References

[edit]
  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 Cafarsite Mineral Data from Webmineral
  3. ^ a b c Cafarsite on Mindat.org
  4. ^ a b c Handbook of Mineralogy