Naumannite Mineral Data

Naumannite Mineral Data +

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General Naumannite Information

Chemical Formula:

Ag2Se

Composition:

Molecular Weight = 294.70 gm

Silver 73.21 % Ag

Selenium 26.79 % Se

______

100.00 %

Empirical Formula:

Ag₂Se

Environment:

In hydrothermal veins associated with other selenides, quartz, and carbonates.

IMA Status:

Valid Species (Pre-IMA) 1845

Locality:

Tilkerode (Abberode) and St. Anreasberg, Harz Mountains, Saxony-Anhalt, Germany Link to MinDat.org Location Data.

Name Origin:

Named for Carl Friedrich Naumann (1797-1873), German mineralogist and crystallographer.

Synonym:

ICSD 15213

PDF 24-1041

Naumannite Image

Images:

Naumannite

Comments: Black crystal of Naumannite in a quartz-lined vug.
Location: DeLamar mine, DeLamar, Owyhee County, Idaho. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Naumannite Crystallography

Axial Ratios:

a:b:c =0.6135:1:1.097

Cell Dimensions:

a = 4.336, b = 7.067, c = 7.753, Z = 4; V = 237.57 Den(Calc)= 8.24

Crystal System:

Orthorhombic - DisphenoidalH-M Symbol (2 2 2) Space Group: P 2₁2₁2₁

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

By Intensity(I/I_o): 2.56(1), 2.66(1), 2.23(0.6),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
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S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Wiegers G A , American Mineralogist , 56 (1971) p.1882-1888, The crystal structure of the low-temperature form of silver selenide

Physical Properties of Naumannite

Cleavage:

[???] Perfect, [???] Perfect, Perfect

Color:

Grayish black, Iron black.

Density:

6.5 - 8, Average = 7.25

Diaphaniety:

Opaque

Fracture:

Sectile - Curved shavings or scrapings produced by a knife blade, (e.g. graphite).

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

2.5 - Finger Nail

Luminescence:

Non-fluorescent.

Luster:

Metallic

Magnetism:

Nonmagnetic

Streak:

black

Optical Properties of Naumannite

RL Anisotrophism:

Distinct but weak, light gray to dark gray.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Naumannite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	36.30	40.70
420 nm	37.00	40.60
440 nm	37.70	40.50
460 nm	38.00	40.20
480 nm	38.10	39.60
500 nm	37.80	38.90
520 nm	37.00	38.10
540 nm	35.70	37.30
560 nm	34.60	36.70
580 nm	33.80	36.20
600 nm	33.20	35.80
620 nm	32.70	35.50
640 nm	32.20	35.00
660 nm	31.80	34.70
680 nm	31.50	34.30
700 nm	31.20	34.80

**Calculated Relative Intensity Colors of Naumannite in Air**
Relative Intensity	0%	30%	60%	90%	100%	120%	150%	180%	210%	240%	270%
R₁
R₂

Calculated Properties of Naumannite

Electron Density:

r_electron=7.16 gm/cc
note: r_Naumannite=8.24 gm/cc.

Fermion Index

Fermion Index = 0.02036
Boson Index = 0.97964

Photoelectric:

PE_Naumannite= 213.70 barns/electron
U=PE_Naumannite x r_electron=1,529.68 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Naumannite is Not Radioactive

Naumannite Classification

Dana Class:

2.4.1.2 (2)Sulfides - Including Selenides and Tellurides

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

(2.4.1)Dana Group

2.4.1.1 Acanthite Ag2S P 2₁/n 2/m

2.4.1.2 Naumannite Ag2Se P 2₁2₁2₁ 2 2 2

2.4.1.3 Aguilarite Ag4SeS P 2₁2₁2₁ 2 2 2

Strunz Class:

II/B.05-30 II - Sulfides and sulphosalts

II/B - Sulfides with metal: sulfur, selenium and tellurium > 1:1, Sulfides, Selenides and Tellurides with predominant Copper and Silver/Gold

II/B.05 - Achantite - Empresite series

II/B.05-02 Argentite* Ag2S I m3m 4/m 3 2/m

II/B.05-10 Acanthite Ag2S P 2₁/n 2/m

II/B.05-30 Naumannite Ag2Se P 2₁2₁2₁ 2 2 2

II/B.05-35 Kurilite* (Ag,Au)2(Te,Se,S) P m3n,P 4₃n Cubic

II/B.05-40 Hessite Ag2Te P 2₁/c 2/m

II/B.05-50 Aguilarite Ag4SeS P 2₁2₁2₁ 2 2 2

II/B.05-60 Cervelleite Ag4TeS Unk Cubic

II/B.05-70 Benleonardite Ag8(Sb,As)Te2S3 Tetra Tetra

II/B.05-75 Tsnigriite Ag9SbTe3(S,Se)3 P 2/m,Pm Mono

II/B.05-80 Stutzite Ag5-xTe3,(x=0.24-0.36) P 6/mmm 6/m 2/m 2/m

II/B.05-90 Empressite AgTe Pmnb 2/m 2/m 2/m

Other Naumannite Information

References:

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

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Naumannite

Ag2Se
Dana No: 2.4.1.2 Strunz No: II/B.05-30
Locality:

Notes: