Quartzite

Physical Properties

Hardness: 7 (Mohs scale), Color: White to grey with reddish-brown iron staining, Luster: Vitreous to dull, Crystal structure: Trigonal/Hexagonal (granular), Cleavage: None, Specific Gravity: 2.6-2.7

Formation & Geological History

Formed through the heating and pressure of sandstone during regional metamorphism. The original quartz sand grains recrystallize into a locked mosaic of quartz crystals. Most quartzite dates back millions of years to mountain-building events.

Uses & Applications

Used in construction as crushed stone for road beds and railway ballast. Due to its hardness and resistance to weathering, it is used for floor tiles, countertops, and as a decorative stone in landscaping.

Geological Facts

Quartzite is so hard that it can scratch steel and even glass easily. Unlike sandstone, which breaks around grains, quartzite breaks through the individual grains due to its high degree of recrystallization.

Field Identification & Locations

Identify in the field by its sugary texture on fresh surfaces and its ability to scratch glass. It is commonly found in fold mountain belts globally, such as the Appalachian Mountains or the Alps.

Identified on: 4/27/2026

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