Arsenopyrite with Quartz
Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
Mineral NameArsenopyrite with Quartz
Chemical FormulaFeAsS
Mohs Hardness5.5
Crystal Systemmonoclinic
Lustermetallic
Streak Colordark grayish black
Cleavagedistinct on {101}
Fractureuneven to conchoidal
Specific Gravity5.9
Colorssilvery white, steel gray, clear, white
Transparencyopaque
Type LocalityPanasqueira, Covilhã, Castelo Branco District, Portugal
Mineral GroupSulfides
Usesore of arsenic, minor ore of gold, collector's item
Associated Mineralsquartz
Rarityuncommon
Description
This specimen features a prominent, clear to milky, terminated quartz crystal rising from a base of numerous silvery-metallic, blocky to prismatic arsenopyrite crystals.
Geological Context
Arsenopyrite is a common hydrothermal mineral found in high-temperature veins, often associated with tin-tungsten deposits like Panasqueira, where it forms alongside quartz and other sulfide minerals. It is a significant ore of arsenic and can be a minor source of gold.
