 |
|
|
Polybasite is an uncommon mineral containing silver and copper in its structure. It is almost always found in known silver deposits, often in association with Stephanite. Polybasite forms a series with Pearceite, with Polybasite being the antimony-rich member, and Pearceite being the arsenic-rich member. It is often not possible to visually distinguish these two minerals from each other. Polybasite is named from the Greek words, poly, "many" and basis, "base" referring to its composition of several metallic and submetallic elements. |
|
|
Chemical Formula |
[(Ag9CuS4)][(Ag,Cu)6Sb2S7] |
|
Composition |
Silver and copper antimony sulfide, often with some arsenic |
| Variable Formula |
[(Ag9CuS4)][(Ag,Cu)6(Sb,As)2S7] |
|
Color |
Dark gray to nearly black. May have occasional internal red reflections or iridescence. |
|
Streak |
Black. May have a red tinge. |
|
Hardness |
2 - 3 |
|
Crystal System |
Monoclinic |
|
|
|
Crystal Forms
and Aggregates |
Most often pseudohexagonal in shape, due to twinning on the prism-planes. Crystals are usually tabular, platy, bladed, or in rosette habit. Often striated with triangular striation patterns. Also grainy, flaky, and massive. |
|
Transparency |
Opaque |
|
Specific Gravity |
6.0 - 6.2 |
|
Luster |
Metallic |
|
Cleavage |
1,1 |
|
Fracture |
Uneven |
|
Tenacity |
Brittle |
|
In Group |
Sulfides; Sulfosalts |
|
Striking Features |
Crystal habits, streak, and mode of occurrence. |
| Environment |
Low temperature epithermal veins in silver ore deposits. |
| Rock Type |
Sedimentary, Metamorphic |
|
Popularity (1-4)
|
3 |
|
Prevalence (1-3)
|
3 |
|
Demand (1-3) |
1 |
|
|
 |
|
|
|
|
|
An ore of silver and rare collector's mineral.
|
Polybasite is not a common mineral. In Europe, well-formed micro hexagonal crystals come from the Clara Mine, Rankach valley, Oberwolfach, Baden-Württemberg, Germany. Small flaky crystals have come from the Příbram area, Bohemia, Czech Republic. In Peru, Polybasite occurs with Pyrargyrite at the Uchucchacua Mine, Oyon Province, Lima Department.
Mexico contains several notable localities for this mineral. Large, well-formed crystals of Polybasite have come from the San Juan de Rayas Mine, Guanajuato; and large single crystals and groups from the Chispas Mine, Arizpe, Sonora. Crystal clusters with Calcite have come from the Proano Mine, Fresnillo, Zacatecas.
Polybasite is very rare in U.S.: Crudely formed crystal clusters have come from the Eagle Mine, Gilman, Eagle Co., Colorado. In Canada, exceptional, well-formed, iridescent crystals came from a small find Husky Mine, Elsa, Galena Hill, Mayo Mining District, Yukon Territory. Small crystals and flakes come from Cobalt, Timiskaming District, Ontario. |
Hematite - Has a greater hardness, redder streak, and is slightly attracted to magnets.Stephanite - Difficult to distinguish, although crystals are usually thicker. Pearcite - Indistinguishable without complex methods.
|
|
|
|
|
|
|
|
Have a question about Polybasite? Visit our Q&A Community and ask the experts!
|
|
|
|
Let us know how we can update this page
(Click for more details)
|
|
We strive for accurate content and locality information. If you feel any of the content is incorrect, or if you feel we are missing vital locality information, please fill out the form below so we can update the site. If you are requesting a locality be added, please only include significant locality occurences for the mineral.
|
 |
| |
|
|
|
|
|
|
|
