Quartz / Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: Milky white to translucent grey; Luster: Vitreous to greasy; Crystal Structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone. Under intense heat and pressure, original quartz grains recrystallize and fuse together into a dense, hard rock. Typically associated with regional metamorphism in mountain-building zones.

Uses & Applications

Used in construction as crushed stone or road ballast, as a refractory material in glassmaking, and frequently collected as a raw mineral specimen. High-purity varieties are used in electronics.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. Quartzite is so tough that it often outlasts the surrounding rock in eroding landscapes, forming prominent ridges and peaks.

Field Identification & Locations

Identify by its ability to scratch glass and steel, its lack of cleavage, and its sugary or grainy texture when broken. It is extremely resistant to chemical weathering and is found globally in mountainous and glaciated regions.

Identified on: 4/29/2026

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