Quartzite with Iron Inclusions

Physical Properties

Hardness: 7 on Mohs scale; Color: Pinkish-orange tan with translucent areas; Luster: Vitreous to greasy; Crystal structure: Trigonal/Hexagonal sub-microscopic; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6 – 2.7.

Formation & Geological History

Formed through the metamorphism of quartz starch sandstone. Under heat and intense pressure (regional metamorphism), quartz grains recrystallize and fuse together. The orange/red hues are caused by iron oxide staining within the rock matrix.

Uses & Applications

Used primarily as decorative gravel, in construction as crushed stone, as a source for silica in glassmaking, or as a polished lapidary specimen for beginner collectors.

Geological Facts

Quartzite is so tough that it usually breaks through the quartz grains themselves rather than around them, unlike its parent rock, sandstone. It is often harder and more durable than granite.

Field Identification & Locations

Identify in the field by its inability to be scratched by a steel knife and its lack of reaction to acid. Often found in riverbeds as rounded 'river rocks' due to water erosion. Common in ancient mountain belts.

Identified on: 4/17/2026

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