Quartzite Pebble (with Iron Staining)

Physical Properties

Hardness: 7 (Mohs scale); Color: Pink to reddish-orange due to hematite/limonite staining, originally white or gray; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: None; Specific gravity: 2.6-2.7

Formation & Geological History

Formed through the metamorphism of quartz sandstone under high heat and pressure, causing quartz grains to recrystallize into an interlocking mosaic. This specific specimen has likely been rounded by water transport (fluvial/glacial) and stained by iron-rich groundwaters.

Uses & Applications

Used in construction as crushed stone or road ballast; higher purity quartzite is used to produce silicon for electronics and glass. Polished pebbles are used for landscaping and aquariums.

Geological Facts

Quartzite is so durable that it often survives intense weathering that destroys other rocks. It is harder than steel and can easily scratch glass. The reddish-orange color is a surface 'patina' of iron oxides.

Field Identification & Locations

Identify in the field by its hardness (it should scratch glass and steel knife blades) and its granular, sugary texture. Unlike sandstone, quartzite fractures across the grains rather than around them. Commonly found in riverbeds and glacial tills.

Identified on: 4/21/2026

Mode: Standard