metamorphic
Quartzite Pebble
Quartzite (composed primarily of SiO2)
Hardness of 7 on the Mohs scale, dull to waxy/vitreous luster, fine-grained microcrystalline texture, dull grayish-brown color with speckling, non-porous and highly resistant to weathering.
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Physical properties
Hardness of 7 on the Mohs scale, dull to waxy/vitreous luster, fine-grained microcrystalline texture, dull grayish-brown color with speckling, non-porous and highly resistant to weathering.
Formation & geological history
Formed when quartz-rich sandstone is subjected to intense heat and pressure during regional metamorphism, recrystallizing the quartz grains into a dense, interconnected matrix. Later rounded by stream or beach action.
Uses & applications
Commonly used in construction aggregate, landscaping, decorative gravel, and as a durable material for stone masonry and tumbling.
Geological facts
Quartzite is so tough that when struck, it breaks across quartz grains rather than along the boundaries between them, unlike sandstone.
Field identification & locations
Look for a smooth, well-rounded pebble shape with microcrystalline grain structure that cannot be scratched by a steel blade. Found extensively along riverbeds, gravel pits, and coastal beaches.
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