Pyrargyrite
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.
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.
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