What is Pyrargyrite?
Pyrargyrite is the dark red silver-antimony sulfosalt known as ruby silver, a classic ore mineral with striking colour and metallic lustre.
Mineralogy and crystal structure
Reference formula: Ag3SbS3. Pyrargyrite is trigonal and the antimony analogue of proustite. It is soft, dense and light-sensitive at the surface; silver content makes assay and provenance important. Pyrargyrite is classified with sulfosalts and has a trigonal crystal system. Typical hardness is 2–2.5 on the Mohs scale and specific gravity is approximately 5.8–6.0.
Colour, lustre and habit
Typical colours include dark red, scarlet, black, grey. The usual rhombohedral, prismatic, massive habit and metallic, adamantine lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Pyrargyrite forms in or is associated with low-temperature hydrothermal silver veins. Important documented localities include Mexico, Chile, Peru, Germany, the Czech Republic, Canada and the United States.
Ruby silver from a hydrothermal vein
Pyrargyrite combines a dramatic name with real ore significance: a dark-red crystal can be both a collector highlight and a clue to silver-rich vein chemistry.
Collecting and care
Keep enclosed and away from strong light, acids and dust; do not grind or use in jewellery without professional preparation.
