Red Quartzite / Ferruginous Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: Reddish-brown to orange-tan; Luster: Vitreous to dull/waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Formation & Geological History

Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. The red coloring is caused by the inclusion of iron oxide (hematite) during or after deposition.

Uses & Applications

Used in landscaping, construction (as crushed stone or decorative facing), and sometimes as a minor gemstone or decorative tumble-stone.

Geological Facts

Quartzite is so hard that it can scratch glass and steel. It is frequently more durable than the parent sandstone from which it originated, often forming resistant ridges in mountain ranges.

Field Identification & Locations

Identify by its extreme hardness (cannot be scratched by a knife) and grainy, crystalline texture that breaks through the grains rather than around them. Common in precambrian shields and eroded mountain belts.

Identified on: 4/13/2026

Mode: Standard