Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons
Pyrargyrite is found in a number of localities in well-formed crystals, but these are usually small. However, larger, transparent crystals from Bolivia and Chile have provided a limited amount of cuttable rough. Stones approaching 50 carats have been cut, but these tend to be too dark to be really attractive. They are exceedingly rare, however, since pyrargyrite is seldom transparent, usually even less so than the related sulfide, proustite.
Pyrargyrite Value
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Pyrargyrite Information
| Data | Value |
| Name | Pyrargyrite |
| Crystallography | Hexagonal (R); crystals prismatic, often hemimorphic. Usually massive, compact, disseminated. |
| Colors | Dark red. |
| Luster | Adamantine. |
| Hardness | 2.5. |
| Density | 5.85. |
| Birefringence | 0.200. |
| Cleavage | Distinct 1 direction. Fracture conchoidal to uneven, brittle. |
| Luminescence | None reported. |
| Spectral | Not diagnostic. |
| Formula | Ag3SbS3. Related to proustite. |
| Pleochroism | None observed. |
Streak: Purplish red.
Optics: o = 3.08; e=2.88- _
(Note: these reported measurements were made using the Li line at 6710 rather than the customary Na line at 5890)
Uniaxial (—).
Occurrence: In low temperature hydrothermal vein deposits, as an important ore of silver.
Freiburg, Germany; Guadalajara, Spain.
Mexico: Guanajuato and Durango.
Colorado; Idaho; Nevada; California.
Ontario, Canada; Czechoslovakia; Chile.
Colquechaca, Bolivia: fine crystals, gemmy.
Comments: Pyrargyrite is found in a number of localities in well-formed crystals, but these are usually small. However, larger, transparent crystals from Bolivia and Chile have provided a limited amount of cuttable rough. Stones approaching 50 carats have been cut, but these tend to be too dark to be really attractive. They are exceedingly rare, however, since pyrargyrite is seldom transparent, usually even less so than the related sulfide, proustite.
Name: From Greek words meaning fire and silver: in allusion to the color and composition.
