mineral

Arsenopyrite

Arsenopyrite (FeAsS)

Hardness: 5.5-6 (Mohs scale); Color: Tin-white to steel-gray, often with a brassy yellow tint; Luster: Metallic; Crystal Structure: Monoclinic (pseudo-orthorhombic); Cleavage: Distinct; Specific Gravity: 5.9–6.2.

Hardness: 5
Color: Tin-white to steel-gray, often with a brassy yellow tint
Luster: Metallic

Identified March 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed in high-temperature hydrothermal veins, pegmatites, and contact metamorphic environments. Most deposits are associated with volcanic activity and hydrothermal fluids rich in arsenic and iron.

Uses & applications

Primary ore of arsenic; used in the production of herbicides, pesticides, and specialized alloys. Occasionally collected as mineral specimens, though toxic if handled improperly.

Geological facts

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

Field identification & locations

Identify by its metallic luster, high density (heavy for its size), and garlic smell when crushed or heated. Common in mining districts of Germany, China, and Canada. Collectors should store it in dry conditions to prevent oxidation.