Quartzite pebble

Hardness 7 on Mohs scale; light brownish-yellow to translucent yellowish-tan color; waxy to vitreous luster; microcrystalline/granoblastic structure; conchoidal to uneven fracture; no cleavage; specific gravity ~2.65.

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, causing quartz grains to recrystallize into a interlocking mosaic of quartz crystals. Subsequently rounded by water erosion.

Used in construction as crushed stone, railway ballast, decorative landscaping gravel, lapidary tumbling, and stone carving.

Quartzite is extremely tough and resistant to chemical weathering. Unlike sandstone, which breaks around quartz grains, quartzite breaks directly through the quartz grains when fractured.

Identified in the field by its hardness (scratches glass and steel), sugar-like sparkling fracture surface, and lack of reaction to acid. Commonly found in riverbeds, gravel pits, glacial deposits, and mountainous metamorphic terrains. Excellent material for rock tumbling.