Quartzite Cobble

Hardness: 7 (Mohs scale), Color: Brownish-red due to iron oxide staining, Luster: Dull to vitreous, Crystal structure: Granoblastic/Non-foliated, Cleavage: None (conchoidal fracture)

Formed from the metamorphism of quartz-rich sandstone subjected to high heat and pressure, typically in orogenic belts. This specific specimen has been further shaped by fluvial (river) or coastal water erosion into a rounded cobble.

Commonly used in construction as crushed stone, road ballast, or decorative landscaping stones. In ancient times, it was used for stone tools due to its hardness and fracture patterns.

Quartzite is so tough that it often outlasts the surrounding rock during erosion, forming resistant ridges or caprocks. It is harder than a steel knife and will easily scratch glass.

Identify in the field by its extreme hardness, grainy texture that resembles sandpaper but feels smooth on water-worn surfaces, and its lack of reaction to acid. Often found in glacial till, riverbeds, and along shorelines.