Quartzite

Hardness: 7 (Mohs scale), Color: Pinkish-tan due to iron oxide impurities, Luster: Vitreous to dull, Crystal structure: Trigonal (granular), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7

Quartzite is formed from the metamorphism of quartz-rich sandstone. Under intense heat and pressure, the original quartz grains recrystallize and fuse together. This specimen appears river-worn or tumbled, indicating secondary erosion transport.

Used in construction for road ballast and flooring, as a source for silica in metallurgy, and occasionally as a decorative gemstone or garden stone when polished.

Quartzite is so tough that it often outlasts the surrounding rocks during erosion, forming ridges or resistant outcrops. It is significantly harder than the sandstone from which it originated.

Identified in the field by its ability to scratch glass and its sugary, granular texture. Unlike sandstone, quartzite breaks across the grains rather than around them. Commonly found in folded mountain belts.