Quartzite

Physical Properties

Hardness: 7 (Mohs scale), Color: White to grey/brown with iron staining, Luster: Vitreous to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None/Conchoidal fracture, Specific gravity: 2.6-2.65

Formation & Geological History

Formed through the regional or contact metamorphism of quartzose sandstone. Under high heat and pressure, quartz grains recrystallize and fuse together. It can be found in mountain belts and cratons globally.

Uses & Applications

Used widely in road construction (aggregate), as a decorative stone in landscaping, for making glass (if high purity), and in building facades.

Geological Facts

Quartzite is so tough that it often creates high ridges and resistant mountains because it weathers much more slowly than surrounding rocks like marble or shale.

Field Identification & Locations

Identify in the field by its extreme hardness (cannot be scratched by steel) and its granulated texture that looks like sand grains but breaks across the grains rather than around them. Common in riverbeds and glacial deposits.

Identified on: 4/27/2026

Mode: Standard