metamorphic
Iron-rich quartzite or ironstone
Ferruginous quartzite; predominantly quartz (SiO₂) with hematite/goethite (Fe₂O₃/FeO(OH))
AI-generated identification · may be incorrectHardness about 6.5–7 for quartz, with earthy iron-oxide coatings; brown, reddish-brown, gray, and metallic-gold patches; generally non-cleaving, granular, with vitreous to dull/earthy luster. The apparent gold is likely reflective mica or iron oxide, not native gold.
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Physical properties
Hardness about 6.5–7 for quartz, with earthy iron-oxide coatings; brown, reddish-brown, gray, and metallic-gold patches; generally non-cleaving, granular, with vitreous to dull/earthy luster. The apparent gold is likely reflective mica or iron oxide, not native gold.
Formation & geological history
Likely metamorphosed quartz-rich sandstone or silica-rich iron formation, with later oxidation producing hematite/goethite; commonly Precambrian to Paleozoic, depending on locality.
Uses & applications
Used as crushed stone, aggregate, and occasionally ornamental material; attractive specimens are collected, but it is not typically a jewelry gemstone.
Geological facts
Iron oxides create the rusty coloration and can form shiny botryoidal or specular surfaces. A streak test, magnet test, and acid test help distinguish it from gold-bearing rock.
Field identification & locations
Common in iron-rich terrains worldwide, including banded-iron-formation regions. It should leave a reddish-brown streak, show no gold malleability, and may weakly attract a magnet if magnetite is present.
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