Sylvanite is the gold-silver telluride, the silver-bearing partner to calaverite. Together with calaverite, it forms the classic gold-mineral pair of the Romanian (Transylvanian) and Colorado (Cripple Creek) telluride deposits.
Properties
- Formula: (Au,Ag)Te2
- Crystal system: Monoclinic
- Hardness: 1.5 – 2
- Color: Steel-gray to silver-white, sometimes with golden tinge
- Streak: Steel-gray
- Luster: Bright metallic
- Cleavage: Perfect on {010}
- Density: 8.0 – 8.2 g/cm³
Occurrence
Type locality: Săcărâmb (Nagyág, Romania) — historic 18th-century discovery in the Carpathian gold-telluride belt. Also Cripple Creek (Colorado), Kalgoorlie (Australia), Vatukoula (Fiji). Often forms branching/dendritic “graphic” patterns in matrix that resemble runic writing — hence the German nickname “Schrift-tellur” (script tellurium).
Identification
Bright silver-gray metallic + extreme density + perfect cleavage + Au-Ag-Te chemistry + characteristic dendritic “runes” pattern in matrix. Distinguish from calaverite (more brassy color, no silver, different crystal habit).
Collector Notes
Săcărâmb sylvanite “graphic” specimens are 18th-century mineralogical heirlooms. Cripple Creek material is the modern American standard. Pair with calaverite for the complete Au-Te telluride set.
Found at these Localities
- Kalgoorlie–Boulder (卡尔古利金碲矿)
- Săcărâmb (Nagyág) (萨卡拉姆布金碲矿)
- Cripple Creek District (克里普尔克里克金矿区)
