metamorphic
Iron-stained quartzite or quartz-rich rock
Quartzite, predominantly SiO₂, colored by iron oxides (hematite/goethite)
AI-generated identification · may be incorrectHardness about 7 Mohs; rusty orange-brown and gray-white, with a dull to vitreous luster. The specimen appears massive and granular, without obvious cleavage; specific gravity typically 2.6–2.7.
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Physical properties
Hardness about 7 Mohs; rusty orange-brown and gray-white, with a dull to vitreous luster. The specimen appears massive and granular, without obvious cleavage; specific gravity typically 2.6–2.7.
Formation & geological history
Formed when quartz-rich sandstone was metamorphosed and recrystallized under heat and pressure, commonly during mountain-building events. Its exact geological age cannot be determined from the photograph.
Uses & applications
Used as crushed aggregate, road stone, building stone, and decorative material; attractive pieces may be collected, though this specimen appears common and ungem-quality.
Geological facts
Iron oxides permeating fractures and grain boundaries create the orange, red, and brown coloration. A steel file should struggle to scratch fresh quartz-rich surfaces.
Field identification & locations
Common in metamorphic belts worldwide, including India, Brazil, the United States, and Scandinavia. Field identification requires a hardness test, inspection for fused quartz grains, and comparison with sandstone; acid produces no reaction.
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