metamorphic

Quartzite pebble

Metamorphic Quartzite (SiO2)

AI-generated identification · may be incorrect

Hardness of 7 on Mohs scale, vitreous to dull luster, color ranging from pinkish-tan to reddish-brown, smooth rounded river-worn texture, non-porous.

Identified July 22, 2026More metamorphic →

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Physical properties

Hardness of 7 on Mohs scale, vitreous to dull luster, color ranging from pinkish-tan to reddish-brown, smooth rounded river-worn texture, non-porous.

Formation & geological history

Formed from sandstone subjected to intense heat and pressure during regional metamorphism, causing quartz grains to recrystallize and interlock tightly. Later eroded and rounded by water transport.

Uses & applications

Used as decorative gravel, in lapidary arts, for stone polishing, and historically as aggregate or building material.

Geological facts

Quartzite is so tough that when it breaks, it fractures right through the quartz grains rather than around them, unlike sandstone.

Field identification & locations

Can be identified by its inability to be scratched by a steel knife, granular quartz appearance, and smooth water-worn pebble surface. Extremely common along riverbeds and beaches worldwide.