Quartzite

Physical Properties

Hardiness: 7 Mohs, Color: Gray, white, reddish-pink, or yellowish; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None, conchoidal fracture; Specific gravity: 2.6-2.7

Formation & Geological History

Formed through the metamorphism of quartz sandstone under high heat and pressure, typically in orogenic belts. This specimen shows iron oxidation (reddish tints) and possibly significant geological age from the Proterozoic or Paleozoic eras.

Uses & Applications

Used as a high-quality decorative stone in construction, counter tops, flooring, railway ballast, and as a source of silica in glass manufacturing and metallurgy.

Geological Facts

Quartzite is so tough that it often outlasts the surrounding rock in weathering processes, forming prominent ridges and peaks. It is often confused with marble, but quartzite can scratch glass while marble cannot.

Field Identification & Locations

Identify in the field by its sugary texture on fresh surfaces and its inability to be scratched by a steel knife. It is common in mountainous regions and shield areas globally.

Identified on: 4/14/2026

Mode: Standard