Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: yellowish-tan to white with iron staining; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none (conchoidal fracture); Specific gravity: 2.63-2.65

Formation & Geological History

Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specimen shows significant rounding consistent with alluvial or river transport.

Uses & Applications

Used primarily as crushed stone for road construction, railroad ballast, and as a raw material for glass and ceramics. Polished varieties are used for countertops and decor.

Geological Facts

Quartzite is so tough that it often outlasts the surrounding stones during erosion, creating prominent ridges. It is harder and more durable than its parent rock, sandstone.

Field Identification & Locations

Identify in the field by its hardness (it will scratch glass) and its sugary, granular texture. Commonly found in riverbeds, glacial tills, and mountain ranges globally.

Identified on: 5/4/2026

Mode: Standard