Cobaltarthurite Mineral Data

General Cobaltarthurite Information

Chemical Formula:

CoFe+++2(AsO4)2(OH)2•4(H2O)

Composition:

Molecular Weight = 533.48 gm

Magnesium 0.46 % Mg 0.76 % MgO

Manganese 1.03 % Mn 1.33 % MnO

Iron 21.98 % Fe 31.43 % Fe₂O₃

Cobalt 5.52 % Co 7.02 % CoO

Arsenic 28.09 % As 43.08 % As₂O₅

Hydrogen 1.83 % H 16.38 % H₂O

Oxygen 41.09 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Co_0.5Mg_0.1Fe³⁺_0.1Mn²⁺_0.1Fe³⁺₂(AsO₄)₂(OH)_1.7�4(H₂O)

Environment:

Secondary mineral in a near surface, sulfide-depleted lens (Dolores showing). (Co-dominant analogue of arthurite; structure)

IMA Status:

Approved IMA 2002 (Dana # Added)

Locality:

Patrana (a village about 10 km east of Mazzarron), Province of Murcia, SE Spain. Link to MinDat.org Location Data.

Name Origin:

Named as the Co-dominant member of the arthurite group.

Synonym:

IMA2001-052

Cobaltarthurite Image

Images:

Cobaltarthurite Arseniosiderite

Comments: Olive-greenish crystalline druse of cobaltarthurite with spherical arseniosiderite.
Location: Pastrana, Mazarrón, Murcia, Spain. Scale: Picture size 1.3 mm.
© Thomas Witzke / Abraxas-Verlag

Cobaltarthurite Crystallography

Axial Ratios:

a:b:c =1.0577:1:0.5741

Cell Dimensions:

a = 10.2635, b = 9.7028, c = 5.5711, Z = 2; beta = 94.207° V = 553.30 Den(Calc)= 3.20

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 2₁/c

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

By Intensity(I/I_o): 7.04(1)(110), 10.2(0.95)(100), 4.81(0.65)(001),3.05(0.6), 4.24(0.6)(111), 2.87(0.55)(311), 2.89(0.25)(221), 4.51(0.2),

Physical Properties of Cobaltarthurite

Cleavage:

None

Color:

Straw yellow, Dark brown.

Density:

3.22

Diaphaneity:

Translucent

Fracture:

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

Habit:

Globular - Spherical, or nearly so, rounded forms (e.g. wavellite).

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Oolitic - < 3mm rounded spherical grains.

Hardness:

3.5-4 - Copper Penny-Fluorite

Luster:

Vitreous - Silky

Streak:

light brownish white

Optical Properties of Cobaltarthurite

Gladstone-Dale:

CI meas= 0.013 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.007 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2396,KPDmeas= 0.2381,KC= 0.2412
Ncalc = 1.77 - 1.78

Optical Data:

Biaxial (+), a=1.741, b=1.762, g=1.797, bire=0.0560

Calculated Properties of Cobaltarthurite

Electron Density:

Bulk Density (Electron Density)=3.08 gm/cc
note: Specific Gravity of Cobaltarthurite =3.20 gm/cc.

Fermion Index:

Fermion Index = 0.0053160916
Boson Index = 0.9946839084

Photoelectric:

PE_{Cobaltarthurite}= 27.71 barns/electron
U=PE_{Cobaltarthurite} x rElectron Density= 85.48 barns/cc.

Radioactivity:

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

Cobaltarthurite Classification

Dana Class:

42.11.18.06 (42)Hydrated Phosphates, etc., Containing Hydroxyl or Halogen

(42.11)where (AB)4 (XO4)3 Zq � x(H2O)

(42.11.18)Whitmoreite Group

42.11.18.01 Whitmoreite FeFe2(PO4)2(OH)2•4(H2O) P 2₁/c 2/m

42.11.18.02 Arthurite CuFe2(AsO4,PO4,SO4)2(O,OH)2•4(H2O) P 2₁/c 2/m

42.11.18.03 Ojuelaite ZnFe2(AsO4)2(OH)2•4(H2O) P 2₁/c 2/m

42.11.18.04 Earlshannonite (Mn,Fe)Fe2(PO4)2(OH)2•4(H2O) P 2₁/c 2/m

42.11.18.05 Gladiusite! Fe2(Fe,Mg)4(PO4)(OH)13•H2O P 2₁/n 2/m

42.11.18.06 Cobaltarthurite! CoFe2(AsO4)2(OH)2•4(H2O) P 2₁/c 2/m

42.11.18.07 Kunatite CuFe2(PO4)2(OH)2•4H2O P 2₁/c 2/m

42.11.18.08 Bendadaite! FeFe2(AsO4)2(OH)2•4H2O P 2₁/c 2/m

Strunz Class:

08.DC.15 08 - PHOSPHATES, ARSENATES, VANADATES

08.D - Phosphates, etc

08.DC -With only medium-sized cations, (OH, etc.):RO4 = 1:1 and < 2:1

08.DC.15 Earlshannonite (Mn,Fe)Fe2(PO4)2(OH)2•4(H2O) P 2₁/c 2/m

08.DC.15 Arthurite CuFe2(AsO4,PO4,SO4)2(O,OH)2•4(H2O) P 2₁/c 2/m

08.DC.15 Ojuelaite ZnFe2(AsO4)2(OH)2•4(H2O) P 2₁/c 2/m

08.DC.15 Whitmoreite FeFe2(PO4)2(OH)2•4(H2O) P 2₁/c 2/m

08.DC.15 Cobaltarthurite! CoFe2(AsO4)2(OH)2•4(H2O) P 2₁/c 2/m

08.DC.15 Kunatite CuFe2(PO4)2(OH)2•4H2O P 2₁/c 2/m

08.DC.15 Bendadaite! FeFe2(AsO4)2(OH)2•4H2O P 2₁/c 2/m

Other Cobaltarthurite Information

References:

NAME( AmMin, Vol 88, p 475) PHYS. PROP.(AmMin, v88, p475; v91, p715) OPTIC PROP.(AmMin, Vol 88, p 475)

See Also:

Links to other databases for Cobaltarthurite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Cobaltarthurite

CoFe+++2(AsO4)2(OH)2•4(H2O)
Dana No: 42.11.18.06 Strunz No: 08.DC.15
Locality:

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