Quartzite

Hardness: 7 (Mohs scale), Color: Pinkish-red to brown, Luster: Dull to vitreous, Structure: Non-foliated, granular, Cleavage: None

Formed from the metamorphism of quartz sandstone under high heat and pressure, typically during mountain-building events (orogeny). This specimen shows rounding from water erosion, likely a river pebble.

Used in construction as a decorative stone, road ballast, and in the production of silica glass or industrial abrasives. Small river pebbles are popular for landscaping.

Quartzite is so tough that it often outlasts the surrounding rocks in a landscape, forming prominent ridges. It is often harder than the steel blade of a knife.

Identify in the field by its hardness (will scratch glass) and its grainy, sandpaper-like texture that does not rub off. Found in Precambrian shield areas and mountainous regions worldwide.