metamorphic
Rounded quartz-rich pebble, likely quartzite
Quartzite (mostly crystalline SiO₂), possibly quartz-rich sandstone
AI-generated identification · may be incorrectTypically Mohs hardness ~7, pale gray to pink/tan, with a vitreous to dull luster and granular interlocking quartz crystals; no obvious cleavage, and high resistance to scratching. The rounded shape indicates water or glacial abrasion, while the surface appears naturally weathered.
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Physical properties
Typically Mohs hardness ~7, pale gray to pink/tan, with a vitreous to dull luster and granular interlocking quartz crystals; no obvious cleavage, and high resistance to scratching. The rounded shape indicates water or glacial abrasion, while the surface appears naturally weathered.
Formation & geological history
Quartzite forms when quartz-rich sandstone is metamorphosed under heat and pressure, commonly during mountain building; ages vary widely from Precambrian to younger rocks. The specimen was likely transported and rounded in a stream, beach, or glacial deposit.
Uses & applications
Crushed quartzite is used for aggregate, road stone, and occasionally decorative building stone; attractive pieces are collected or used in lapidary work. This specimen appears modestly ornamental rather than gem quality.
Geological facts
A steel knife should not scratch true quartzite, though it may leave a metallic streak. White or pink coloration commonly reflects quartz, feldspar, and minor iron oxides.
Field identification & locations
Look for a hard, quartz-sparkling granular texture and resistance to scratching; acid produces no reaction. Common in mountain belts and river or glacial gravels worldwide, but exact identification from the photo is limited.
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