Quartz / Quartzite

Physical Properties

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

Formation & Geological History

Quartzite is formed when quartz-rich sandstone is subjected to high heat and pressure during metamorphism. Pure quartz crystals often precipitate from hydrothermal veins or cool from silica-rich magma.

Uses & Applications

Used in the glass industry, as an abrasive, in construction as crushed stone, and as a semi-precious gemstone in jewelry (amethyst, citrine, etc.). It is also vital for electronics due to its piezoelectric properties.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. It was historically used to make stone tools because it fractures into sharp pieces (conchoidal fracture).

Field Identification & Locations

Identify in the field by its inability to be scratched by a steel blade, its lack of reaction to acid, and its glassy luster on fresh surfaces. It is found globally in almost all rock types and environments.

Identified on: 4/15/2026

Mode: Standard