Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: typically white to gray, can be pink or red; Luster: vitreous to dull; Crystal structure: hexagonal; Cleavage: none; Specific gravity: 2.6 - 2.8.

Formation & Geological History

Quartzite forms through the metamorphism of quartz-rich sandstone. High heat and pressure Recrystallize the quartz grains, interlocking them into a dense, hard rock.

Uses & Applications

Used in construction for road ballast, roofing tiles, and decorative stone. Sometimes used for countertops and as a source of silica for glass manufacturing.

Geological Facts

Quartzite is so hard that it can scratch steel and glass easily. It is often mistake for marble, but unlike marble, it does not react with acid.

Field Identification & Locations

Identify in the field by its sugary texture on fresh surfaces and its ability to scratch glass. Found globally in mountainous regions where tectonic forces have compressed sedimentary layers.

Identified on: 4/29/2026

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