metamorphic
Tumbled quartzite pebble
Quartzite, predominantly crystalline SiO₂
AI-generated identification · may be incorrectHardness about 7 Mohs; pale gray-white to tan, smooth matte-to-subvitreous luster, with fine granular quartz texture and no obvious cleavage. The rounded shape indicates natural abrasion or tumbling.
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Physical properties
Hardness about 7 Mohs; pale gray-white to tan, smooth matte-to-subvitreous luster, with fine granular quartz texture and no obvious cleavage. The rounded shape indicates natural abrasion or tumbling.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during regional metamorphism, commonly during Precambrian to Phanerozoic mountain-building. This specimen was likely rounded in a river, beach, or tumbler.
Uses & applications
Used as durable aggregate, paving and building stone, landscaping gravel, and occasionally as a decorative or lapidary pebble. This small common specimen has little commercial value.
Geological facts
Quartzite is generally more resistant to weathering than its original sandstone and can preserve sedimentary layering or cross-bedding. It may resemble quartz, chert, or marble but is typically harder than marble.
Field identification & locations
Identify it by its sugary quartz texture, lack of fizz with dilute acid, and ability to scratch glass; a steel blade usually will not scratch it. Common sources include metamorphic mountain belts and stream gravels worldwide.
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