Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: typically white to gray, often with yellow or tan staining from iron oxides; Luster: vitreous to dull; Crystal structure: Non-foliated, interlocking granoblastic texture; Cleavage: none (conchoidal fracture).

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together. It can be found in tectonic mountain belts of various geological ages.

Uses & Applications

Used as a decorative stone in landscaping, as crushed stone for road construction, and historically for making stone tools due to its hardness and fracture pattern.

Geological Facts

Quartzite is so tough that it often breaks through the constituent quartz grains rather than around them, which distinguishes it from sandstone.

Field Identification & Locations

Identify in the field by its extreme hardness (it will easily scratch glass) and its granular, sugary texture. It is extremely weather-resistant and often forms prominent ridges or hilltops.

Identified on: 4/14/2026

Mode: Standard