metamorphic
Quartzite Pebble
Metamorphic Quartzite (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, grayish-purple color, sub-vitreous to greasy luster, massive crystal structure with interlocking quartz grains, no true cleavage, specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, grayish-purple color, sub-vitreous to greasy luster, massive crystal structure with interlocking quartz grains, no true cleavage, specific gravity around 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert that has been subjected to high heat and pressure, typically during regional metamorphism in mountain-building events.
Uses & applications
Used in landscaping, road construction, decorative gravel, and occasionally as a raw material for crushed stone or refractory bricks.
Geological facts
Quartzite is extremely durable and resistant to weathering, which is why quartz-rich rocks often survive as smooth, rounded pebbles long after other rock types have eroded away.
Field identification & locations
Found frequently in riverbeds, glacial tills, and beaches where water action rounds the durable stone. Easily identified in the field by its scratch resistance to steel and its granular, sugary fracture surface.
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