mineral

Arsenopyrite in Quartz/Host Rock

Arsenopyrite (FeAsS)

Hardness: 5.5-6.0; Color: Silver-white to steel gray with yellowish tarnish; Luster: Metallic; Crystal Structure: Monoclinic; Cleavage: Distinct; Specific Gravity: 5.9-6.2.

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

Identified April 7, 2026More mineral →

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Physical properties

Hardness: 5.5-6.0; Color: Silver-white to steel gray with yellowish tarnish; Luster: Metallic; Crystal Structure: Monoclinic; Cleavage: Distinct; Specific Gravity: 5.9-6.2.

Formation & geological history

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

Uses & applications

Primary source of arsenic for industrial uses; historical source of poison; indicator mineral for gold prospecting; collector specimen.

Geological facts

Arsenopyrite is the most common arsenic-bearing mineral. When struck with a hammer, it often emits a strong garlic-like odor, which is the smell of toxic arsenic fumes.

Field identification & locations

Identify by its metallic silver/goldish appearance and sharp, wedge-like crystals. Often found in quartz veins near igneous intrusions. Use caution: wash hands after handling due to arsenic content.

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