mineral
Pyrite-bearing quartz vein fragment
Quartz (SiO₂) with pyrite (FeS₂), possibly minor chalcopyrite
AI-generated identification · may be incorrectGray-white, granular quartz matrix with brassy metallic sulfide grains; quartz hardness 7, pyrite 6–6.5, metallic luster, no prominent cleavage, and typical pyrite cubic or massive crystal structure. The yellow-orange metallic area may indicate chalcopyrite or oxidized sulfide.
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Physical properties
Gray-white, granular quartz matrix with brassy metallic sulfide grains; quartz hardness 7, pyrite 6–6.5, metallic luster, no prominent cleavage, and typical pyrite cubic or massive crystal structure. The yellow-orange metallic area may indicate chalcopyrite or oxidized sulfide.
Formation & geological history
Formed when silica- and sulfur-rich hydrothermal fluids deposited quartz and sulfide minerals in fractures, commonly in igneous or metamorphic host rocks. The specimen’s precise age cannot be determined from the image.
Uses & applications
Primarily a mineral-collecting specimen; pyrite is historically used as a sulfur and iron source, while quartz has extensive glass, electronics, and industrial uses. Attractive pieces may be used decoratively.
Geological facts
Pyrite is commonly called “fool’s gold,” but it is harder, paler, and less malleable than native gold. Chalcopyrite’s iridescent or golden color can resemble gold and often tarnishes quickly.
Field identification & locations
Look for hard, glassy gray quartz enclosing brassy opaque grains; pyrite may show cubic faces and produces a dark streak, whereas gold leaves a yellow streak and is very malleable. Common worldwide in hydrothermal veins, especially Peru, Mexico, Spain, and the United States.
