metamorphic

Quartzite pebble

Quartzite (primarily SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: Cream, tan, and white, Luster: Vitreous to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture)

Identified April 23, 2026More metamorphic →

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Physical properties

Hardness: 7 (Mohs scale), Color: Cream, tan, and white, Luster: Vitreous to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture)

Formation & geological history

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically in orogenic belts. This smooth shape is the result of mechanical weathering in a high-energy water environment (river or beach).

Uses & applications

Used in construction, as railway ballast, for decorative landscaping, and occasionally as a source of silica for glass manufacturing.

Geological facts

Quartzite can be older than a billion years; it is so hard that it can scratch steel and glass easily. It is often more resistant to weathering than the surrounding rock types.

Field identification & locations

Identify in the field by its hardness (it will scratch a knife blade) and its smooth, rounded texture which indicates travel in water. Commonly found in riverbeds and on coastal shorelines.