metamorphic

Quartzite / Sandstone

Quartzite (SiO2)

AI-generated identification · may be incorrect

Mohs hardness of 6.5 to 7. Light beige, tan, grey, and off-white in color with dull to vitreous luster. Granular, sugary texture composed primarily of fused quartz grains, crossed by thin fracture lines. Non-porous and very durable.

Identified July 24, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed from quartz-rich sandstone through heat, pressure, and regional metamorphism, or heavy silica cementation (orthoquartzite). Commonly weathered into smooth cobbles by river or wave action.

Uses & applications

Widely used in construction as crushed stone, ballast, building stone, decorative landscaping rocks, and flagstone. Highly valued for its hardness and weather resistance.

Geological facts

Unlike sandstone, quartzite breaks through its component quartz grains rather than around them, resulting in a smooth fracture surface despite its granular appearance.

Field identification & locations

Identified by its sugary granular texture, extreme hardness (scratches glass), and resistance to acid. Commonly found in riverbeds, glacial tills, and mountainous metamorphic terrains.