Quartzite Pebble

Physical Properties

Hardness: 7 (Mohs scale); Color: Grayish-white to tan; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Conchoidal fracture; Specific gravity: 2.6-2.7

Formation & Geological History

Formed from quartzose sandstone through heat and pressure (metamorphism) during mountain-building events. This specific specimen has been further shaped into a smooth pebble by fluvial (river) or glacial transport.

Uses & Applications

Commonly used as high-grade construction aggregate, railway ballast, and in the production of silica glass. Smoothed pebbles like this are popular for landscaping decoration and aquarium substrate.

Geological Facts

Quartzite is so tough that it often survives deep into the earth's crust while surrounding rocks erode. It is often harder and more durable than the parent sandstone from which it originated.

Field Identification & Locations

Identify in the field by its ability to easily scratch glass and its rounded, water-worn texture. Found globally in riverbeds, glacial tills, and beaches. For collectors, it is a basic teaching specimen for metamorphism.

Identified on: 4/22/2026

Mode: Standard