
mineral
Gold-bearing dark rock, possibly magnetite with iron-oxide staining
Likely magnetite (Fe₃O₄) with limonite/goethite; metallic patches may be gold or weathered sulfide, unconfirmed
AI-generated identification · may be incorrectBlack, dense, submetallic to metallic surface with rusty brown alteration and pale metallic flecks. Magnetite has Mohs hardness 5.5–6.5, black streak, strong magnetism, and specific gravity about 5.2; visible gold cannot be confirmed visually.
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Physical properties
Black, dense, submetallic to metallic surface with rusty brown alteration and pale metallic flecks. Magnetite has Mohs hardness 5.5–6.5, black streak, strong magnetism, and specific gravity about 5.2; visible gold cannot be confirmed visually.
Formation & geological history
Likely an iron-rich vein or altered igneous/metamorphic fragment formed by hydrothermal mineralization, then oxidized near the surface; its geological age cannot be determined from the photograph.
Uses & applications
Magnetite is an iron ore and industrial pigment; gold-bearing specimens can have collector value, but this piece requires testing before any jewelry or economic use.
Geological facts
A strong magnet test, streak test on unglazed porcelain, and specific-gravity measurement are useful. Gold is soft, nonmagnetic, yellow, and leaves a yellow streak, whereas pyrite is harder and brittle.
Field identification & locations
Commonly found in iron-ore deposits, volcanic terrains, metamorphic belts, and placer settings worldwide. Test with a magnet and hardness comparison; assay or XRF is needed to verify gold.