metamorphic
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
Hardness: 7 (Mohs scale), Color: light grey to tan with translucent bands, Luster: vitreous to waxy, Crystal structure: Hexagonal (microcrystalline), Cleavage: none, Specific gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: light grey to tan with translucent bands, Luster: vitreous to waxy, Crystal structure: Hexagonal (microcrystalline), Cleavage: none, Specific gravity: 2.65
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under high heat and pressure, typically during mountain-building events. These pebbles are often tumbled and smoothed in riverbeds or coastal environments.
Uses & applications
Used primarily as decorative landscaping stone, in construction aggregates, or as tumbled stones for hobbyists and aquarium decor.
Geological facts
Quartzite is so hard that it will scratch glass and steel. It is more resistant to weathering than the sandstone it originated from, which is why it often survives as rounded pebbles long after other rocks have eroded.
Field identification & locations
Identify in the field by its hardness (it won't be scratched by a knife) and its grainy, sugary texture when broken. Commonly found in glaciated areas, river beds, and along beaches.
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