metamorphic
Gold-bearing quartz vein rock (probable pyrite-bearing quartzite)
Quartz (SiO₂) with probable pyrite (FeS₂) and possible native gold
AI-generated identification · may be incorrectGray, fine- to medium-grained, massive and weakly veined; quartz has Mohs hardness 7, glassy to dull luster, and no cleavage. The brassy yellow flecks may be pyrite (hardness 6–6.5) rather than gold; apparent gold cannot be confirmed from the image.
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Physical properties
Gray, fine- to medium-grained, massive and weakly veined; quartz has Mohs hardness 7, glassy to dull luster, and no cleavage. The brassy yellow flecks may be pyrite (hardness 6–6.5) rather than gold; apparent gold cannot be confirmed from the image.
Formation & geological history
Likely formed when silica- and sulfide-rich hydrothermal fluids filled fractures in older rock, later hardened and weathered at the surface; age depends on the deposit, commonly Precambrian to Cenozoic.
Uses & applications
Quartz vein rock is mainly a collector specimen; crushed quartz may be used as aggregate or silica feedstock. If genuinely gold-bearing, it has assay value, but visible flecks alone do not establish economic grade.
Geological facts
Pyrite is brittle and commonly forms angular grains or cubes, while native gold is soft, malleable, and bright yellow. A laboratory fire assay or professional XRF is needed to verify gold.
Field identification & locations
Common in hydrothermal vein districts worldwide, including Nevada, California, Australia, Canada, and South Africa. Test suspected gold only professionally; avoid relying on color or a streak test alone.
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