Quartzite with Iron Inclusions

Physical Properties

Hardness: 7 (Mohs scale), Color: Reddish-brown, tan, and gray, Luster: Vitreous to dull, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.6-2.7

Formation & Geological History

Formed through the metamorphism of quartz sandstone under high heat and pressure, which causes the sand grains to recrystallize into a dense interlaced structure. The red/brown coloring comes from iron-rich mineral staining during or after formation.

Uses & Applications

Used primarily in construction as road ballast, railway beds, and decorative stone. High-quality quartzite is used in glassmaking and as a refractory material.

Geological Facts

Quartzite is so tough that it often survives intense weathering that wears away surrounding rocks. It is harder than most other rocks and will easily scratch steel or glass. This specific specimen shows 'iron-rich staining' suggesting it was near a water source or iron deposit.

Field Identification & Locations

Identify in the field by its hardness (cannot be scratched by a steel blade) and its sugary texture. Unlike sandstone, quartzite fractures across its grains rather than around them. Commonly found in mountainous regions or ancient shield areas.

Identified on: 4/25/2026

Mode: Standard