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Sylvanite

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Formula:
(Au,Ag)2Te4
Au:Ag ratio usually is close to 1:1
System:
Monoclinic
Colour:
Grey, white, pale yellow ...
Lustre:
Metallic
Hardness:
1½ - 2
Name:
Named in 1835 by Louis Albert Necker-de Saussure for the Transylvania region of Romania, where it was first found, and Sylvanium, one of the names proposed for the newly discovered element tellurium, which it contains.
Compare krennerite.


Classification of Sylvanite

Approved, 'Grandfathered' (first described prior to 1959)
2.EA.05

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
E : Metal Sulfides, M: S <= 1:2
A : M:S = 1:2 - With Cu, Ag, Au
2.12.13.3

2 : SULFIDES
12 : AmBnXp, with (m+n):p = 1:2
3.3.9

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

Physical Properties of Sylvanite

Metallic
Transparency:
Opaque
Colour:
Grey, white, pale yellow silver-white
Streak:
Silver-white
Hardness:
1½ - 2 on Mohs scale
Hardness:
VHN100=154 - 172 kg/mm2 - Vickers
Tenacity:
Brittle
Cleavage:
Perfect
on {010}
Fracture:
Irregular/Uneven
Density:
8.16 g/cm3 (Measured)    8.161 g/cm3 (Calculated)

Optical Data of Sylvanite

Type:
Anisotropic
Anisotropism:
Very strong
Colour in reflected light:
Creamy white
Pleochroism:
Strong
Comments:
Cream white to leather brown.

Chemical Properties of Sylvanite

Formula:
(Au,Ag)2Te4

Au:Ag ratio usually is close to 1:1
IMA Formula:
AgAuTe4
Common Impurities:
Sb,Pb,Cu,Ni

Crystallography of Sylvanite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P2/b
Cell Parameters:
a = 8.95(1) Å, b = 4.478(5) Å, c = 14.62(2) Å
β = 145.35(5)°
Ratio:
a:b:c = 1.999 : 1 : 3.265
Unit Cell V:
333.14 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Short prismatic, thick tabular, skeletal, bladed, columnar, granular.
Twinning:
Common on {100}

Crystallographic forms of Sylvanite

Crystal Atlas:
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Sylvanite - {100}, {010}, {101}, highly modified
Sylvanite - {100}, {010}, {-101}, {-103}, highly modified
3d models and HTML5 code kindly provided by www.smorf.nl.

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Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

View
Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation

X-Ray Powder Diffraction

Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Type Occurrence of Sylvanite

Common Associates

Associated Minerals Based on Photo Data:
Quartz114 photos of Sylvanite associated with Quartz on mindat.org.
Gold52 photos of Sylvanite associated with Gold on mindat.org.
Coloradoite43 photos of Sylvanite associated with Coloradoite on mindat.org.
Hessite39 photos of Sylvanite associated with Hessite on mindat.org.
Fluorite27 photos of Sylvanite associated with Fluorite on mindat.org.
Calaverite9 photos of Sylvanite associated with Calaverite on mindat.org.
Petzite9 photos of Sylvanite associated with Petzite on mindat.org.
Laumontite7 photos of Sylvanite associated with Laumontite on mindat.org.
Tellurium6 photos of Sylvanite associated with Tellurium on mindat.org.
Apatite6 photos of Sylvanite associated with Apatite on mindat.org.

Related Minerals - Nickel-Strunz Grouping

2.EA.10CalaveriteAuTe2
2.EA.15KostoviteCuAuTe4
2.EA.15KrenneriteAu3AgTe8
2.EA.20BerndtiteSnS2
2.EA.20KitkaiteNiTeSe
2.EA.20MeloniteNiTe2
2.EA.20Merenskyite(Pd,Pt)(Te,Bi)2
2.EA.20Moncheite(Pt,Pd)(Te,Bi)2
2.EA.20ShuangfengiteIrTe2
2.EA.20SudovikovitePtSe2
2.EA.25VerbeekitePdSe2
2.EA.30DrysdalliteMo(Se,S)2
2.EA.30JordisiteMoS2
2.EA.30MolybdeniteMoS2
2.EA.30TungsteniteWS2

Related Minerals - Hey's Chemical Index of Minerals Grouping

3.3.1CalaveriteAuTe2
3.3.2KrenneriteAu3AgTe8
3.3.3KostoviteCuAuTe4
3.3.4UytenbogaardtiteAg3AuS2
3.3.5FischesseriteAg3AuSe2
3.3.6PetrovskaiteAuAg(S,Se)
3.3.7PetziteAg3AuTe2
3.3.8MuthmanniteAuAgTe2
3.3.10Penzhinite(Ag,Cu)4Au(S,Se)4
3.3.11Bezsmertnovite(Au,Ag)4Cu(Te,Pb)
3.3.12BilibinskitePbCu2Au3Te2
3.3.13Bogdanovite(Au,Te,Pb)3(Cu,Fe)
3.3.14Montbrayite(Au,Sb)2Te3

Related Minerals - Dana Grouping (8th Ed.)

2.12.13.1KrenneriteAu3AgTe8
2.12.13.2CalaveriteAuTe2
2.12.13.4KostoviteCuAuTe4

Synonyms of Sylvanite

Other Language Names for Sylvanite

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.

References for Sylvanite

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
von Reichenstein (1785) Phys. Arb. Wien: 3: 48.
von Born (1790) 2: 467.
Klaproth, M.H. (1802) Chemische Untersuchung der siebenbürgischen Golderze, B. Schrifterz, Beiträge zur chemischen Kenntniss der Mineralkörper, Dritter Band, Rottmann Berlin, 16-19.
Necker (1835) Sylvanit. [?]
Palache, C. (1900) American Journal of Science: 10: 419.
Spencer (1903) Mineralogical Magazine: 13: 271.
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: 338-341.
American Mineralogist (1949) 34: 342.
Tschermaks Mineralogische und Petrographische Mitteilungen (1984) 33: 203-212.

Internet Links for Sylvanite

mindat.org URL:
https://www.mindat.org/min-3849.html
Please feel free to link to this page.
Specimens:
The following Sylvanite specimens are currently listed for sale on minfind.com.

Localities for Sylvanite

Mineral and/or Locality  
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