metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale), Color: yellowish-orange with grey and pinkish tones from iron oxides and impurities, Luster: dull to vitreous, Crystal structure: microcrystalline/granular, Specific gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: yellowish-orange with grey and pinkish tones from iron oxides and impurities, Luster: dull to vitreous, Crystal structure: microcrystalline/granular, Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under high heat and pressure, causing quartz grains to recrystallize into a dense interlocking matrix. This specimen is a river-rounded or glacial-washed pebble.
Uses & applications
Primarily used in construction (crushed stone), as railway ballast, and occasionally for lapidary work or as decorative garden stones.
Geological facts
Quartzite is so hard and durable that it often resists weathering better than the rocks around it, leading to its common occurrence as well-rounded river pebbles or high-standing ridges.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sandpaper-like texture that doesn't rub off. It lacks the distinct layering of sandstone or the visible individual grains of granite. Found globally in ancient mountain belts.
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