mineral
Gold-bearing quartz in a dark host rock (possible gold-in-quartz specimen)
Quartz (SiO₂) with possible native gold (Au) in a fine-grained host; exact identification is uncertain from the photo
AI-generated identification · may be incorrectThe rounded specimen has a dark, fine-grained matrix and a yellow, metallic-looking patch. Quartz is Mohs 7 with vitreous luster and no cleavage; native gold is Mohs 2.5–3, malleable, and strongly metallic. The yellow area could also be iron staining or another sulfide, not gold.
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Physical properties
The rounded specimen has a dark, fine-grained matrix and a yellow, metallic-looking patch. Quartz is Mohs 7 with vitreous luster and no cleavage; native gold is Mohs 2.5–3, malleable, and strongly metallic. The yellow area could also be iron staining or another sulfide, not gold.
Formation & geological history
Quartz veins form when silica-rich fluids fill fractures, sometimes depositing gold as they cool; the dark matrix may be volcanic or metamorphic rock. Age and formation setting cannot be determined from the image.
Uses & applications
Gold-bearing quartz is collected and, when confirmed and sufficiently rich, processed for gold; attractive specimens are kept as display pieces.
Geological facts
Gold is malleable and leaves a yellow streak, while pyrite is brittle and commonly leaves a dark streak. A photo alone cannot confirm native gold.
Field identification & locations
Check whether the yellow material is metallic and malleable rather than flaky or brittle; definitive identification requires testing or assay. Gold-bearing quartz occurs in many regions, including California, Australia, and South Africa.
