metamorphic

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Off-white to light gray with dark inclusions; Luster: Vitreous to waxy; Structure: Granular/Crystalline; Cleavage: None; Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Off-white to light gray with dark inclusions
Luster: Vitreous to waxy

Identified July 15, 2026More metamorphic →

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Physical properties

Hardness: 7 on Mohs scale; Color: Off-white to light gray with dark inclusions; Luster: Vitreous to waxy; Structure: Granular/Crystalline; Cleavage: None; Specific Gravity: 2.65.

Formation & geological history

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specimen has been rounded by fluvial (river) or glacial erosion.

Uses & applications

Raw quartzite is used in construction, road ballast, and as a source of silica for glass manufacturing. Smooth pebbles are popular for landscaping and aquarium decor.

Geological facts

Quartzite is so tough that it often outlasts the surrounding rocks in a landscape, forming resistant ridges. It is often confused with marble, but quartzite will scratch glass and won't fizz in acid.

Field identification & locations

Identify by its extreme hardness and granular texture. Look for it in riverbeds, glacial tills, or mountain outcrops. For collectors, look for unique colors or translucent qualities.