Proustite
Image: <a href="//commons.wikimedia.org/w/index.php?title=User:Parent_G%C3%A9ry&action=edit&redlink=1" class="new" title="User:Parent Géry (page does not exist)">Parent Géry</a> (Public domain)
Mineral NameProustite
Chemical FormulaAg3AsS3
Mohs Hardness2
Crystal Systemtrigonal
Lusteradamantine
Streak Colorred (vermilion)
Cleavagedistinct on {1011}
Fractureconchoidal
Specific Gravity5.57
Colorsruby-red, scarlet, purplish-red, dark gray (tarnished)
Transparencytransparent
Type LocalityFreiberg, Saxony, Germany; Chañarcillo, Chile; Cobalt, Ontario, Canada
Mineral GroupSulfosalts
Usesminor ore of silver, collector
Associated Mineralsnative silver, galena, sphalerite, calcite, quartz, pyrargyrite
Rarityuncommon
Description
This image displays a cluster of dark purplish-red proustite crystals exhibiting a submetallic to adamantine luster, appearing almost black in some areas due to tarnish or lighting, set on a light-colored matrix.
Geological Context
Proustite is a low-temperature hydrothermal mineral that forms in silver-rich veins, typically found in the late stages of mineralization in epithermal deposits.
