metamorphic
Quartz-rich metamorphic rock, likely quartzite
Quartzite; predominantly crystalline quartz (SiO₂), possibly with mica, feldspar, and iron-oxide staining
AI-generated identification · may be incorrectHardness about 7 Mohs; pale gray, cream, and tan with brown weathering; vitreous to dull luster and granular, interlocking quartz crystals. Typically lacks cleavage, breaks irregularly, and has specific gravity near 2.65;…
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Physical properties
Hardness about 7 Mohs; pale gray, cream, and tan with brown weathering; vitreous to dull luster and granular, interlocking quartz crystals. Typically lacks cleavage, breaks irregularly, and has specific gravity near 2.65; the visible layered texture could also indicate quartz-rich schist or strongly metamorphosed sandstone.
Formation & geological history
Forms when quartz-rich sandstone is recrystallized under heat and pressure during mountain-building; individual specimens commonly range from Precambrian to Paleozoic age depending on locality. Exact identification and age require a fresh surface and locality information.
Uses & applications
Durable quartzite is used as crushed stone, aggregate, building stone, paving, and countertops; attractive pieces are collected but this rough specimen has little gem value.
Geological facts
A steel file should barely scratch it, while quartzite can scratch ordinary glass. Acid typically produces no fizz unless carbonate minerals are present.
Field identification & locations
Look for fused quartz grains, high hardness, and resistance to weathering; a sugary granular texture supports quartzite, whereas obvious aligned mica flakes suggest quartz-mica schist. Common in metamorphic mountain belts worldwide.
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