Quartzite with Hematite staining

Hardness: 7 (Mohs scale), Color: tan with reddish-purple staining, Luster: Vitreous to dull, Crystal structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture)

Formed through the regional or contact metamorphism of quartz-rich sandstone. High heat and pressure causes quartz grains to recrystallize. The red coloration is due to iron oxide (hematite) impurities.

Used in construction as road ballast, crushed stone, and decorative landscaping. High-purity quartzite is used in the manufacture of glass and silicon products.

Quartzite is so tough that it often survives intense weathering better than other rocks, frequently capping mountains and ridges. The red staining from hematite is a common characteristic when iron-rich water permeates the rock structure.

Identify in the field by its hardness (will scratch glass and steel) and its granular, sugary texture. Unlike sandstone, it breaks through the grains rather than around them. Commonly found in folded mountain belts globally.