Arsenopyrite
Image: <a href="//commons.wikimedia.org/wiki/User:Islam90" title="User:Islam90">Islam90</a> (CC BY-SA 4.0)
Mineral NameArsenopyrite
Chemical FormulaFeAsS
Mohs Hardness5.5
Crystal Systemmonoclinic
Lustermetallic
Streak Colordark grayish black
Cleavagedistinct on {101}
Fractureuneven
Specific Gravity6.07
Colorssilver-white, steel-gray
Transparencyopaque
Type LocalityVarious worldwide, including Freiberg (Germany), Panasqueira (Portugal), and many gold deposits.
Mineral GroupSulfides
Usesore of arsenic, minor ore of gold (when associated)
Associated Mineralspyrite, chalcopyrite, galena, sphalerite, quartz, gold
Raritycommon
Description
The image shows a microscopic view of arsenopyrite, appearing as a bright, reflective, anhedral to subhedral grain under reflected light, surrounded by a darker matrix. Macroscopically, it typically forms silvery-white to steel-gray crystals with a metallic luster.
Geological Context
Arsenopyrite is a common hydrothermal mineral found in high-temperature veins, contact metamorphic deposits, and pegmatites. It often occurs in association with gold deposits, serving as a significant host for refractory gold.
