Quartzite Pebble

Hardness: 7 (Mohs scale), Color: Creamy white to light tan, Luster: Vitreous to waxy, Crystal structure: Trigonal/Hexagonal (microcrystalline), Cleavage: None/Conchoidal fracture, Specific gravity: 2.63-2.65

Formed through the metamorphism of quartz-rich sandstone. High heat and pressure reciprocal to tectonic activities cause individual quartz grains to recrystallize into a locked mosaic. This specific specimen has been further shaped into a smooth pebble by fluvial (river) or glacial transport.

Used in construction as road ballast and concrete aggregate. High-purity quartzite is used in glass making and electronics. Polished pebbles are popular for landscaping and decorative aquariums.

Quartzite is so durable that it often survives intense erosion that wears away surrounding softer rocks. On a Mohs scale, it is harder than a steel knife and can easily scratch glass.

Identify in the field by its hardness (it will scratch glass) and its granular, sugary texture on a fresh break. Commonly found in riverbeds, glaciated regions, and ancient mountain belts. It is one of the most chemically resistant and durable rocks on Earth's surface.