Quartzite Pebble

Physical Properties

Hardness (Mohs scale): 7; Color: light gray to tan; Luster: dull to vitreous; Crystal structure: granular/interlocking quartz grains; Cleavage: none; Specific gravity: approx. 2.65

Formation & Geological History

Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specimen has been smoothed and rounded by river or coastal erosion (fluvial or marine processes).

Uses & Applications

Used primarily as construction aggregate, road ballast, and decorative landscaping stones. Highly rounded pebbles are often used in ornamental gardens.

Geological Facts

Quartzite is so tough that it usually breaks through the quartz grains rather than around them, unlike sandstone. It is one of the most durable and weather-resistant rocks on the Earth's surface.

Field Identification & Locations

Identify by its extreme hardness (it will scratch glass) and lack of visible grains typical of sandstone. Commonly found in riverbeds, beaches, and glacial till. High-quality pieces feel extremely dense and smooth.

Identified on: 5/14/2026

Mode: Standard