Quartzite (Gold/Tan River Cobble)

Physical Properties

Hardness: 7 on Mohs scale; Color: Tan, golden-brown, beige; Luster: Dull to vitreous; Crystal Structure: Granular/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Formation & Geological History

Formed from the metamorphism of quartz sandstone under intense heat and pressure, often during mountain-building events. This specific specimen is a water-worn river cobble, rounded by fluvial erosion.

Uses & Applications

Used in construction as crushed stone or road ballast, as a refractory material in industrial furnaces, and occasionally as decorative landscaping stone.

Geological Facts

Quartzite is so hard that it can scratch glass and steel. It is one of the most durable and weather-resistant rocks on the Earth's surface.

Field Identification & Locations

Identify in the field by its extreme hardness, granular 'sugary' texture on fresh breaks, and resistance to chemical weathering. Extremely common in riverbeds and glacial tills globally.

Identified on: 4/25/2026

Mode: Standard