Alloclasite Mineral Data

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.

Name Pronunciation:

Alloclasite + Pronunciation

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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drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
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S - Stereo Pair on/off
H - Help Screen
I - Data Info
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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

Diaphaneity:

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:

Bulk Density (Electron Density)=5.63 gm/cc
note: Specific Gravity of Alloclasite =6.14 gm/cc.

Fermion Index:

Fermion Index = 0.0032484804
Boson Index = 0.9967515196

Photoelectric:

PE_Alloclasite= 45.20 barns/electron
U=PE_Alloclasite x rElectron Density= 254.61 barns/cc.

Radioactivity:

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

Alloclasite Classification

Dana Class:

02.12.06.02 (02)Sulfides - Including Selenides and Tellurides

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

(02.12.06)Dana Group

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

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

Strunz Class:

02.EB.10b 02 - SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulf

02.E - Metal Sulfides, M:S £ 1:2

02.EB -M:S = 1:2, with Fe, Co, Ni, PGE, etc.

02.EB.10b 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)

See Also:

Links to other databases for Alloclasite :
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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Print or Cut-and-Paste your Alloclasite Specimen Label here :

Alloclasite

(Co,Fe)AsS
Dana No: 02.12.06.02 Strunz No: 02.EB.10b
Locality:

Notes: