Pyrargyrite: Gemstone Information

Pyrargyrite is Ag3SbS3 and forms translucent deep red prismatic crystals of the trigonal system, showing hemimorphism and adamantine lustre.They may darken on exposure to light. The hardness is 2.5 and the SG 5.85. The RI for the ordinary and extraordinary rays is 3.08 and 2.88, uniaxial negative, birefringence 0.200. Pyrargyrite occurs in hydrothermal veins as a primary late-stage low-temperature mineral. Fine crystals are found at Chanarcillo, Atacama, Chile and from Colquechaca, Potosi,
Bolivia.