Quartzite with Iron Inclusions

Physical Properties

Hardness: 7 (Mohs scale); Color: White, gray, or reddish-brown due to iron oxidation; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular texture); Cleavage: None; Specific gravity: 2.6 - 2.8

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. This specimen appears as a water-worn river pebble, likely dating back to the Proterozoic or Paleozoic eras.

Uses & Applications

Used in construction as crushed stone or ballast, in glass manufacturing if high purity, and as decorative stone for landscaping or aquariums.

Geological Facts

Quartzite is so tough that it usually breaks through the quartz grains rather than along their boundaries, unlike its parent sandstone. The reddish staining is known as 'desert varnish' or iron oxide staining.

Field Identification & Locations

Identify in the field by its hardness (will scratch glass) and its sugary, crystalline fracture surface. Commonly found in riverbeds, glacial deposits, or mountain ranges with high tectonic activity.

Identified on: 5/1/2026

Mode: Standard