Chalcocite Mineral Data

General Chalcocite Information

Chemical Formula:

Cu2S

Composition:

Molecular Weight = 159.16 gm

Copper 79.85 % Cu

Sulfur 20.15 % S

______

100.00 %

Empirical Formula:

Cu₂S

Environment:

Secondary mineral in or near the oxidized zone of copper sulfide deposits.

IMA Status:

Valid Species (Pre-IMA) 1832

Locality:

Cornwall, England and Butte, Montana. Link to MinDat.org Location Data.

Name Origin:

From the Greek, meaning chalkos, "copper".

Name Pronunciation:

Chalcocite + Pronunciation

Synonym:

Cocinerite - mixture with silver

Chalcocite Image

Images:

Chalcocite

Comments: Chalcocite crystals in this specimen vary in size up to 1.2 cm across.
Location: Bristol nr. Hartford, Connecticut, USA. Scale: 7.6 x 4 cm.
© John Veevaert

Images:

Eskolaite Chalcocite

Comments: Green crystalline eskolaite on massive chalcocite.
Location: Lubelin, Poland. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Chalcocite Crystallography

Axial Ratios:

a:b:c =0.4348:1:0.4937

Cell Dimensions:

a = 11.881, b = 27.323, c = 13.491, Z = 96; beta = 116.35° V = 3,924.48 Den(Calc)= 6.46

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): 1.88(1), 1.9746(0.7), 2.403(0.7),

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Forms: ( 0 1 0) ( 0 1 2) ( 1 1 3) ( 1 1 0) ( 0 0 1)

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Physical Properties of Chalcocite

Cleavage:

{110} Indistinct

Color:

Blue black, Gray, Black, Black gray, Steel gray.

Density:

5.5 - 5.8, Average = 5.65

Diaphaneity:

Opaque

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Euhedral Crystals - Occurs as well-formed crystals showing good external form.

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

2.5-3 - Finger Nail-Calcite

Luminescence:

Non-fluorescent.

Luster:

Metallic

Magnetism:

Nonmagnetic

Streak:

grayish black

Optical Properties of Chalcocite

RL Anisotrophism:

Weak.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Chalcocite in Air**
λ	R	∑ R(λ)
400 nm	37.40
420 nm	36.70
440 nm	36.00
460 nm	35.20
480 nm	34.40
500 nm	33.50
520 nm	32.60
540 nm	31.80
560 nm	31.00
580 nm	30.20
600 nm	29.60
620 nm	29.00
640 nm	28.40
660 nm	28.00
680 nm	27.20
700 nm	27.10

**Calculated Relative Intensity Colors of Chalcocite in Air**
Relative Intensity	0%	40%	80%	100%	120%	160%	200%	240%	280%	300%
R

Calculated Properties of Chalcocite

Electron Density:

Bulk Density (Electron Density)=6.01 gm/cc
note: Specific Gravity of Chalcocite =6.46 gm/cc.

Fermion Index:

Fermion Index = 0.0015110456
Boson Index = 0.9984889544

Photoelectric:

PE_Chalcocite= 37.21 barns/electron
U=PE_Chalcocite x rElectron Density= 223.51 barns/cc.

Radioactivity:

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

Chalcocite Classification

Dana Class:

02.04.07.01 (02)Sulfides - Including Selenides and Tellurides

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

(02.04.07)Chalcocite Group ([Cu]2-x S] formulae)

02.04.07.01 Chalcocite Cu2S P 2₁/c 2/m

02.04.07.02 Djurleite Cu31S16 P 2₁/n 2/m

02.04.07.03 Digenite Cu9S5 R 3m 3 2/m

02.04.07.04 Roxbyite Cu1.78S C 2/m 2/m

02.04.07.05 Anilite Cu7S4 P nma 2/m 2/m 2/m

02.04.07.06 Geerite Cu8S5 R 3m, R 3m, or R 32 Trig

02.04.07.07 Spionkopite Cu1.4S P 3m1 ? 3m

Strunz Class:

02.BA.05a 02 - SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulf

02.B - Metal Sulfides, M:S > 1:1 (mainly 2:1)

02.BA -With Cu, Ag, Au

02.BA.05a Chalcocite Cu2S P 2₁/c 2/m

Other Chalcocite Information

References:

NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1)

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

Chalcocite

Cu2S
Dana No: 02.04.07.01 Strunz No: 02.BA.05a
Locality:

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