Alloclasite Mineral Data

Alloclasite Mineral Data +

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General Alloclasite Information

Chemical Formula:

(Co,Fe)AsS

Composition:

Molecular Weight = 165.15 gm

Iron 8.45 % Fe

Cobalt 26.76 % Co

Arsenic 45.37 % As

Sulfur 19.42 % S

______

100.00 %

Empirical Formula:

Co_0.75Fe²⁺_0.25AsS

Environment:

In calcite or quartz veins of apparently low temperature, late stage hydrothermal origin. Also in silicified, recrystallized metamorphic rock.

IMA Status:

Valid Species (Pre-IMA) 1866

Locality:

In the Elizabeth mine, Oravita (Oravicza), Romania. From the Silverfields mine, Cobalt, and the Siscoe mine, Miller Lake, Gowganda, Ontario, Canada. Link to MinDat.org Location Data.

Name Origin:

From the Greek for "other", and "to break," because its cleavage was believed to be different from marcasite, which it resembles.

Synonym:

ICSD 36395

PDF 25-246

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Alloclasite Crystallography

Axial Ratios:

a:b:c =0.8316:1:0.6091

Cell Dimensions:

a = 4.662, b = 5.606, c = 3.415, Z = 2; V = 89.25 Den(Calc)= 6.14

Crystal System:

Orthorhombic - DisphenoidalH-M Symbol (2 2 2) Space Group: P 22121

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

By Intensity(I/I_o): 2.75(1), 2.47(0.9), 1.82(0.7),

Crystal Structure:

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drag2 - RMB Resize/Rotate
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Scott J D , Nowacki W , The Canadian Mineralogist , 14 (1976) p.561-566, The crystal structure of alloclasite, CoAsS, and the, alloclasite-cobaltite transformation

Physical Properties of Alloclasite

Cleavage:

[101] Perfect, [010] Distinct

Color:

Steel gray.

Density:

6.17

Diaphaniety:

Opaque

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Habit:

Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)

Hardness:

5 - Apatite

Luster:

Metallic

Streak:

black

Optical Properties of Alloclasite

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Alloclasite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	47.20	49.20
420 nm	47.50	49.60
440 nm	47.80	50.00
460 nm	48.20	50.40
480 nm	48.70	50.90
500 nm	49.10	51.30
520 nm	49.40	51.50
540 nm	49.30	51.50
560 nm	49.10	51.30
580 nm	48.70	51.00
600 nm	48.10	50.60
620 nm	47.60	50.10
640 nm	47.20	49.80
660 nm	46.90	49.50
680 nm	46.70	49.20
700 nm	46.60	49.00

**Calculated Relative Intensity Colors of Alloclasite in Air**
Relative Intensity	0%	20%	40%	60%	80%	100%	120%	140%	160%	180%	190%
R₁
R₂

Calculated Properties of Alloclasite

Electron Density:

r_electron=5.63 gm/cc
note: r_Alloclasite=6.14 gm/cc.

Fermion Index

Fermion Index = 0.00324
Boson Index = 0.99676

Photoelectric:

PE_Alloclasite= 45.20 barns/electron
U=PE_Alloclasite x r_electron= 254.61 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Alloclasite is Not Radioactive

Alloclasite Classification

Dana Class:

2.12.6.2 (2)Sulfides - Including Selenides and Tellurides

(2.12)where Am Bn Xp, with (m+n):p=1:2

(2.12.6)Dana Group

2.12.6.1 Glaucodot (Co,Fe)AsS C mmm 2/m 2/m 2/m

2.12.6.2 Alloclasite (Co,Fe)AsS P 22121 2 2 2

Strunz Class:

II/D.22-60 II - Sulfides and sulphosalts

II/D - Sulfides with metal: sulfur, selenium and tellurium < 1:1, Tellurides with Copper, Silver, Gold

II/D.22 - Arsenopyrite series

II/D.22-10 Arsenopyrite FeAsS P 2₁/c 2/m

II/D.22-20 Glaucodot (Co,Fe)AsS C mmm 2/m 2/m 2/m

II/D.22-30 Gudmundite FeSbS P 2₁/n 2/m

II/D.22-40 Ruarsite RuAsS P 2₁/c 2/m

II/D.22-50 Osarsite (Os,Ru)AsS P 2₁/c 2/m

II/D.22-60 Alloclasite (Co,Fe)AsS P 22121 2 2 2

Other Alloclasite Information

References:

NAME( AntBidBlaNic1) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1)

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

Alloclasite

(Co,Fe)AsS
Dana No: 2.12.6.2 Strunz No: II/D.22-60
Locality:

Notes: