metamorphic

Quartzite Pebble

Metamorphic Quartzite (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: Tan/brown/buff; Luster: Sub-vitreous to dull (weathered); Crystal structure: Hexagonal (microcrystalline); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Tan/brown/buff
Luster: Sub-vitreous to dull (weathered)

Identified July 14, 2026More metamorphic →

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Physical properties

Hardness: 7 (Mohs scale); Color: Tan/brown/buff; Luster: Sub-vitreous to dull (weathered); Crystal structure: Hexagonal (microcrystalline); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Formation & geological history

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specimen has been rounded by fluvial or glacial erosion.

Uses & applications

Primarily used in construction (railway ballast, crushed stone), glass manufacturing, and as decorative landscaping stones.

Geological facts

Quartzite is so tough that it often survives the complete erosion of the original mountain range it formed in, ending up as pebbles in distant riverbeds. It is harder than steel and can scratch glass easily.

Field identification & locations

Identify in the field by its extreme hardness and smooth, water-worn texture. Common in riverbeds and glacial tills across North America and Europe. Collectors look for unique colors or internal banding.