mineral

Arsenopyrite

Arsenopyrite (FeAsS)

AI-generated identification · may be incorrect

Hardness: 5.5-6.0; Color: Silver-white to steel-gray; Luster: Metallic; Crystal Structure: Monoclinic; Cleavage: Distinct; Specific Gravity: 6.07; Streak: Black.

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

Identified April 6, 2026More mineral →

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Physical properties

Hardness: 5.5-6.0; Color: Silver-white to steel-gray; Luster: Metallic; Crystal Structure: Monoclinic; Cleavage: Distinct; Specific Gravity: 6.07; Streak: Black.

Formation & geological history

Formed in high-temperature hydrothermal veins, pegmatites, and contact metamorphic deposits. It is often found associated with gold, quartz, and other sulfides.

Uses & applications

Primary ore of arsenic; historically used to produce arsenic trioxide for pesticides and pigments. Occasionally collected as specimens or for its gold content in associated deposits.

Geological facts

When struck with a hammer, arsenopyrite emits a strong garlic-like odor due to the release of arsenic vapors. It is known as 'mispickel' in older geological literature.

Field identification & locations

Identify in the field by its metallic silver-gray color, high density, and garlic smell when crushed. Common in mining districts such as Cornwall (UK), Germany, and Ontario (Canada).