Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: Gray, white, or yellowish; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None; Specific gravity: 2.6-2.7

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone subjected to high heat and pressure. Most specimens are Proterozoic to Paleozoic in age, occurring in orogenic belts.

Uses & Applications

Used as crushed stone for road construction, railway ballast, and in the manufacturing of glass and ceramics. Polished pieces are used for countertops and floor tiles.

Geological Facts

Quartzite is so hard and chemically resistant that it often forms the ridges and peaks of mountain ranges because it resists weathering better than surrounding rocks.

Field Identification & Locations

Identify by its ability to scratch glass and its granular, sugary texture. Found abundantly in mountain ranges and glacial deposits worldwide. Collectors look for unique colorations.

Identified on: 5/15/2026

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