metamorphic
Gold-bearing quartz vein rock (likely pyrite-rich quartzite)
Quartz (SiO₂) with iron sulfides, chiefly pyrite (FeS₂), possibly chalcopyrite (CuFeS₂); gold cannot be confirmed visually
AI-generated identification · may be incorrectHardness about 6–7 for quartz and 6–6.5 for pyrite; gray-white quartz with brassy metallic grains, granular texture, and no obvious cleavage. Specific gravity varies widely, roughly 2.65–5.0 depending on sulfide content; true native gold is much softer (2.5–3) and notably dense.
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Physical properties
Hardness about 6–7 for quartz and 6–6.5 for pyrite; gray-white quartz with brassy metallic grains, granular texture, and no obvious cleavage. Specific gravity varies widely, roughly 2.65–5.0 depending on sulfide content; true native gold is much softer (2.5–3) and notably dense.
Formation & geological history
Formed when silica- and sulfide-rich hydrothermal fluids filled fractures, later altered or metamorphosed; the rock may range from Precambrian to much younger depending on locality. Gold, if present, occurs as microscopic or visible native metal within quartz and sulfides.
Uses & applications
Used mainly as a mineral specimen or exploration sample; gold-bearing material has economic value only after assay and processing. It is not generally suitable for construction.
Geological facts
Brassy metallic grains are commonly pyrite (“fool’s gold”) or chalcopyrite rather than gold. Gold typically leaves a yellow streak and is malleable, while pyrite produces a dark greenish-black streak and crumbles or fractures.
Field identification & locations
Look for glassy quartz, metallic sulfides, rusty iron-oxide staining, and dense yellow metal; avoid relying on color alone. Common in hydrothermal gold districts worldwide, including Nevada, California, Australia, Canada, and South Africa.
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