mineral

Arsenic (Native)

Arsenic (As)

Hardness: 3.5 on Mohs scale; Color: Tin-white on fresh surfaces, tarnishing quickly to dark gray or black; Luster: Metallic; Crystal structure: Trigonal (rhombohedral); Cleavage: Perfect basal; Specific gravity: 5.6-5.8.

Hardness: 3
Luster: Metallic

Identified April 10, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins alongside other arsenic minerals, silver, and cobalt. Often found in botryoidal (grape-like) or granular masses rather than distinct crystals. Typically formed in low-to-moderate temperature environments.

Uses & applications

Primarily used as a source of arsenic for industrial alloys, wood preservatives, and historical uses in medicinal compounds and pesticides. Highly valued as a mineral specimen for collectors despite its toxicity.

Geological facts

Native arsenic is toxic and can cause skin irritation or internal poisoning if handled improperly. When heated, it gives off a distinct garlic-like odor and sublimes from a solid directly into a gas.

Field identification & locations

Identify in the field by its high density, metallic luster that tarnishes black, and the garlic smell when struck or heated (avoid inhaling fumes). Found in mining districts like the Harz Mountains in Germany and various sites in Japan.