Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: white to light tan/yellow; Luster: vitreous to grainy; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture).

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone subjected to high heat and pressure. This recrystallizes the quartz grains into a dense, interlocking mosaic.

Uses & Applications

Used in construction as crushed stone or road ballast, as a decorative building stone, and historically for stone tools due to its hardness.

Geological Facts

Quartzite is so tough that it often survives intense weathering better than surrounding rocks, frequently forming the caps of ridges and mountain peaks.

Field Identification & Locations

Identify in the field by its extreme hardness (it will easily scratch glass) and its grainy, sugary texture. Unlike sandstone, it breaks across the grains rather than around them.

Identified on: 4/21/2026

Mode: Standard