mineral

Arsenopyrite

Arsenopyrite (FeAsS)

Hardness: 5.5-6.0; Color: Silver-white to steel gray; Luster: Metallic; Crystal Structure: Monoclinic; Cleavage: Distinct; Specific Gravity: 5.9-6.2. Emits a strong garlic-like odor when struck or heated.

Hardness: 5
Color: Silver-white to steel gray
Luster: Metallic

Identified April 27, 2026More mineral →

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Physical properties

Formation & geological history

Formed in high-temperature hydrothermal veins, pegmatites, and contact metamorphic deposits. It is often found associated with gold, tin, and tungsten ores.

Uses & applications

Primary ore of arsenic; used in herbicides, wood preservatives, and lead-alloys. Minor source of gold when found in auriferous deposits.

Geological facts

Arsenopyrite is known as 'mispickel'. It is the most common mineral containing arsenic. The garlic smell it produces when struck is due to the release of arsenic vapors.

Field identification & locations

Identify by its high specific gravity, metallic luster, and the characteristic garlic smell when crushed. Commonly found in mining districts in Cornwall, Germany, China, and Canada.