Quartzite Pebble

Physical Properties

Hardness: 7 (Mohs scale), Color: Yellowish-brown (tan/buff), Luster: Vitreous to waxy, Crystal structure: Trigonal/Hexagonal (microcrystalline), Cleavage: None/Conchoidal fracture, Specific gravity: 2.6 – 2.7

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize and fuse together. This specific specimen has been further shaped into a 'river pebble' through water erosion over long periods.

Uses & Applications

Used in construction as crushed stone or gravel, as high-purity silica for glassmaking, in landscaping, and occasionally as decorative stones or lapidary material.

Geological Facts

Quartzite is so tough that it often outlasts the surrounding rocks in a landscape, leading to it forming ridges or occurring as durable pebbles in riverbeds far from its source. It is harder than steel and will easily scratch glass.

Field Identification & Locations

Identify in the field by its extreme hardness (cannot be scratched by a knife) and its grainy, sugary texture on freshly broken surfaces. Found frequently in riverbeds, glacial deposits, or mountainous regions.

Identified on: 4/25/2026

Mode: Standard