Quartzite Pebble

Physical Properties

Hardness: 7 on Mohs scale; Color: Yellowish-tan to grey; Luster: Vitreous to dull (weathered); Crystal structure: Hexagonal/Trigonal (crystalline); Cleavage: None (conchoiodal fracture); Specific Gravity: 2.6-2.7

Formation & Geological History

Formed through the metamorphism of quartz sandstone under high heat and pressure, causing recrystallization into a dense, interlocking mosaic of quartz crystals. This water-worn pebble likely dates from hundreds of millions of years ago.

Uses & Applications

Used in construction as road ballast or decorative stone; high-purity quartzite is a source of silica for glassmaking and metallurgical uses.

Geological Facts

Quartzite is so durable that it can survive long-distance transport in rivers and high-energy coastal environments that would pulverize most other rock types. It is harder than steel.

Field Identification & Locations

Identify by its extreme hardness (cannot be scratched by a steel blade) and its granular, sugary texture on fresh breaks. This specific specimen shows river-worn 'chatter marks' or impact crescents on the surface.

Identified on: 4/27/2026

Mode: Standard