Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: typically white to gray, with yellowish-brown iron staining common; Luster: vitreous to dull; Structure: non-foliated, granular; Specific Gravity: 2.6-2.7

Formation & Geological History

Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize and fuse together, typically in mountain-building geological environments.

Uses & Applications

Used as a decorative stone, crushed stone for road construction and ballast, and occasionally in glassmaking or as a semi-precious stone for lapidary work.

Geological Facts

Quartzite is so hard and durable that it often forms the resistant ridges and hilltops of mountain ranges. It is harder than steel and will easily scratch glass.

Field Identification & Locations

Identify by its hardness (cannot be scratched by a steel nail) and grainy, sugary texture. Common in ancient mountain belts like the Appalachians or the Alps.

Identified on: 5/3/2026

Mode: Standard