metamorphic
Polished yellow-brown quartzite or jasper
Quartz-rich quartzite; possibly iron-stained jasper (microcrystalline SiO₂)
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs, opaque to slightly translucent, honey-brown with pale mottling, and a vitreous to waxy polish. Massive and non-cleaving; exact identification is limited by the photograph.
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Physical properties
Hardness about 6.5–7 Mohs, opaque to slightly translucent, honey-brown with pale mottling, and a vitreous to waxy polish. Massive and non-cleaving; exact identification is limited by the photograph.
Formation & geological history
Quartzite forms when quartz-rich sandstone is metamorphosed under heat and pressure; jasper forms from silica-rich sediments or volcanic fluids. These materials commonly formed during Precambrian to younger geological events.
Uses & applications
Used as a tumbled or polished ornamental stone, cabochon, carving material, and lapidary specimen; quartzite is also used as aggregate and building stone.
Geological facts
The rounded triangular shape and glossy surface indicate human cutting and polishing. Yellow-brown coloration commonly results from iron oxides or hydroxides.
Field identification & locations
Likely identification can be tested by its inability to scratch glass only if unusually altered; a steel file should not scratch it, while quartz or a glass plate may scratch it. Common sources include Brazil, India, Madagascar, and the western United States.
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