Cafarsite Mineral Data

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General Cafarsite Information

Chemical Formula:

Ca8(Ti,Fe++,Fe+++,Mn)6-7(As+++O3)12•4(H2O)

Composition:

Molecular Weight = 2,230.31 gm

Calcium 14.38 % Ca 20.11 % CaO

Titanium 7.51 % Ti 12.54 % TiO₂

Manganese 1.23 % Mn 1.59 % MnO

Iron 7.51 % Fe 6.44 % FeO / 3.58 % Fe₂O₃

Arsenic 40.31 % As 53.22 % As₂O₃

Hydrogen 0.36 % H 3.23 % H₂O

Oxygen 28.69 % O

______ ______

100.00 % 100.72 % = TOTAL OXIDE

Empirical Formula:

Ca₈Ti_3.5Fe²⁺₂Fe³⁺Mn²⁺_0.5(AsO₃)₁₂•4(H₂O)

Environment:

On cleft faces in orthogneiss.

IMA Status:

Approved IMA 1966

Locality:

West flank of Cherbadung [Pizzo Cervandone], Binntal, Valais, Switzerland. Link to MinDat.org Location Data.

Name Origin:

Named for the elements in the composition, CAlcium, iron (Ferrum), and ARSenic.

Name Pronunciation:

Cafarsite + Pronunciation

Synonym:

ICSD 200144

PDF 19-197

Cafarsite Image

Images:

Cafarsite

Comments: Octahedron of cafarsite with a green coloration (?) on a gneiss matrix.
Location: Vasl D' Aosta, Italy. Scale: 4.6x4.5x3.2 cm.
© Isaias Casanova / IC Minerals

Images:

Cafarsite

Comments: Small, cubic crystal of cafarsite on matrix.
Location: Wannigletscher, Binntal, Switzerland. Scale: Crystal size 0.5 cm.
© Rob Lavinsky

Cafarsite Crystallography

Cell Dimensions:

a = 16.01, Z = 4; V = 4,103.69 Den(Calc)= 3.61

Crystal System:

Isometric - DiploidalH-M Symbol (2/m 3) Space Group: P n3

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.83(1), 2.75(0.8), 3.15(0.7),

Crystal Structure:

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Edenharter A , Nowacki W , Weibel M , Schweizerische Mineralogische und Petrographische Mitteilungen , 57 (1977) p.1-16, Zur struktur und zusammensetzung von cafarsit, cafarsit ein As(III)-oxid,, kein arsenat, Locality: synthetic, Note: Water positions were not determined

Physical Properties of Cafarsite

Cleavage:

None

Color:

Brownish yellow, Brownish black, Dark brown, Dark red.

Density:

3.9

Diaphaneity:

Translucent to Opaque

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Hardness:

5.5-6 - Knife Blade-Orthoclase

Luster:

Sub Metallic

Streak:

yellowish brown

Optical Properties of Cafarsite

Optical Data:

NCalc= 1.92 - from Gladstone-Dale relationship (KC = 0.2541) where Ncalc=Dcalc*KC+1
NCalc= 1.99 - from Gladstone-Dale relationship (KC = 0.2541) where Ncalc=Dmeas*KC+1

Calculated Properties of Cafarsite

Electron Density:

Bulk Density (Electron Density)=3.40 gm/cc
note: Specific Gravity of Cafarsite =3.61 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Cafarsite= 33.41 barns/electron
U=PE_Cafarsite x rElectron Density= 113.73 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Cafarsite is Not Radioactive

Cafarsite Classification

Dana Class:

45.01.04.01 (45)Acid and normal Antimonites, Arsenites and Phosphites

(45.01)with miscellaneous formulae

(45.01.04)Dana Group

45.01.04.01 Cafarsite Ca8(Ti,Fe,Fe,Mn)6-7(AsO3)12•4(H2O) P n3 2/m 3

Strunz Class:

04.JC.05 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate

04.J - Arsenites, Antimonites, Bismuthites, Sulfites,

04.JC -Arsenites, antimonites, bismuthites; without additional anions, with H2O

04.JC.05 Cafarsite Ca8(Ti,Fe,Fe,Mn)6-7(AsO3)12•4(H2O) P n3 2/m 3

Other Cafarsite Information

References:

NAME( AntBidBlaNic4) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Cafarsite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Ask about Cafarsite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
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Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Cafarsite Specimen Label here :

Cafarsite

Ca8(Ti,Fe++,Fe+++,Mn)6-7(As+++O3)12•4(H2O)
Dana No: 45.01.04.01 Strunz No: 04.JC.05
Locality:

Notes: