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Naumannite

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Karl Friedrich Naumann
Formula:
Ag2Se
System:
Orthorhombic
Colour:
grey-black
Hardness:
Name:
after Georg Amadeus Carl Friedrich Naumann (30 May 1797 – 26 November 1873), German crystallographer and geologist
Compare the chemically similar aguilarite.

Classification of Naumannite

Approved, 'Grandfathered' (first described prior to 1959)
2.BA.55

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
B : Metal Sulfides, M: S > 1: 1 (mainly 2: 1)
A : With Cu, Ag, Au
2.4.1.2

2 : SULFIDES
4 : AmBnXp, with (m+n):p = 2:1
3.2.3

3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
2 : Sulphides etc. of Ag
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Type Occurrence of Naumannite

Occurrences of Naumannite

Geological Setting:
hydrothermal veins deficient in sulfur.

Physical Properties of Naumannite

Metallic
Diaphaneity (Transparency):
Opaque
Colour:
grey-black
Comment:
tarnishes to iridescent brownish
Streak:
black
Hardness (Mohs):
Hardness (Vickers):
VHN25=33 - 84 kg/mm2
Tenacity:
Sectile
Cleavage:
None Observed
Fracture:
Hackly
Density:
7.0 - 8.0 g/cm3 (Measured)    8.24 g/cm3 (Calculated)

Crystallography of Naumannite

Crystal System:
Orthorhombic
Class (H-M):
2 2 2 - Disphenoidal
Space Group:
P21 21 21
Cell Parameters:
a = 4.333Å, b = 7.062Å, c = 7.764Å
Ratio:
a:b:c = 0.614 : 1 : 1.099
Unit Cell Volume:
V 237.58 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Granular massive
X-Ray Powder Diffraction Data:
d-spacingIntensity
2.67 (100)
2.57 (100)
2.24 (60)
2.006 (40)
4.15 (20)
2.42 (20)
2.11 (20)

Optical Data of Naumannite

Type:
Anisotropic
Anisotropism:
Distinct but weak, pale gray to dark gray

Chemical Properties of Naumannite

Formula:
Ag2Se
All elements listed in formula:
Common Impurities:
Pb,S

Relationship of Naumannite to other Species

2.BA.05ChalcociteCu2S
2.BA.05DjurleiteCu31S16
2.BA.05GeeriteCu8S5
2.BA.05RoxbyiteCu9S5
2.BA.10AniliteCu7S4
2.BA.10DigeniteCu9S5
2.BA.15BorniteCu5FeS4
2.BA.20BellidoiteCu2Se
2.BA.20BerzelianiteCu2Se
2.BA.25AthabascaiteCu5Se4
2.BA.25UmangiteCu3Se2
2.BA.30RickarditeCu7Te5
2.BA.30WeissiteCu2-xTe
2.BA.35AcanthiteAg2S
2.BA.40MckinstryiteAg5-xCu3+xS4
2.BA.40StromeyeriteAgCuS
2.BA.40dUM2003-13-S:AgAuCuAg6AuCu2S5
2.BA.45JalpaiteAg3CuS2
2.BA.45SelenojalpaiteAg3CuSe2
2.BA.50EucairiteAgCuSe
2.BA.55AguilariteAg4SeS
2.BA.60CervelleiteAg4TeS
2.BA.60HessiteAg2Te
2.BA.60ChenguodaiteAg9Fe3+Te2S4
2.BA.65Henryite(Cu,Ag)3+xTe2 , with x ~ 0.40
2.BA.65StütziteAg5-xTe3, x = 0.24-0.36
2.BA.70ArgyroditeAg8GeS6
2.BA.70CanfielditeAg8SnS6
2.BA.70Putzite(Cu4.7Ag3.3)GeS6
2.BA.75FischesseriteAg3AuSe2
2.BA.75Penzhinite(Ag,Cu)4Au(S,Se)4
2.BA.75PetrovskaiteAuAg(S,Se)
2.BA.75PetziteAg3AuTe2
2.BA.75UytenbogaardtiteAg3AuS2
2.BA.80Bezsmertnovite(Au,Ag)4Cu(Te,Pb)
2.BA.80BilibinskitePbCu2Au3Te2
2.BA.80Bogdanovite(Au,Te,Pb)3(Cu,Fe)
3.2.1AcanthiteAg2S
3.2.4AguilariteAg4SeS
3.2.5HessiteAg2Te
3.2.6EmpressiteAgTe
3.2.7StütziteAg5-xTe3, x = 0.24-0.36
3.2.8CervelleiteAg4TeS
3.2.9DervilliteAg2AsS2
3.2.10StromeyeriteAgCuS
3.2.11MckinstryiteAg5-xCu3+xS4
3.2.12JalpaiteAg3CuS2
3.2.13EucairiteAgCuSe
3.2.14CameroniteCu5-x(Cu,Ag)3+xTe10 (x = 0.43)
3.2.15Henryite(Cu,Ag)3+xTe2 , with x ~ 0.40
3.2.16SternbergiteAgFe2S3
3.2.17ArgentopyriteAgFe2S3
3.2.18Geffroyite(Cu,Fe,Ag)9(Se,S)8
3.2.19ArgentopentlanditeAg(Fe,Ni)8S8

Other Names for Naumannite

Name in Other Languages:
German:Naumannit
Simplified Chinese:硒银矿
Spanish:Naumannita

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Silver ore

References for Naumannite

Reference List:
Rose, G. (1828): Über ein neues Selenerz vom Harz.- Poggendorffs Annalen der Physik und Chemie 14, 471-473.

Haidinger, W. (1845): Zweite Klasse: Geogenide. XIV. Ordnung. Glanze. III. Silberglanz. Naumannit. In: Handbuch der bestimmenden Mineralogie, Braumüller and Seidel, Wien, 563-570.

Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged, 834pp.: 179-180.

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

Petruk, W.; Owens, D. R.; Stewart, J. M.; Murray, E. J. (1974) Observations on acanthite, aguilarite and naumannite. Canadian Mineralogist, 12, 365-369.

Pingitore N E, Ponce B F, Eastman M P, Moreno F, Podpora C (1992) Solid solutions in the system Ag2S-Ag2Se. Journal of Material Research 7, 2219-2224

Billeter, H. & Ruschewitz, U. (2008): Structural phase transitions in Ag2Se (naumannite). Zeitschrift für Anorganische und Allgemeine Chemie 634, 241-246 (in German).

Yu, J. and Yun, H. (2011): Reinvestigation of the low-temperature form of Ag2Se (naumannite) based on single-crystal data. Acta Crystallogr. E67, i45.

Internet Links for Naumannite

Localities for Naumannite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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