metamorphic
Quartzite Pebble
Quartzite (SiO2-dominated rock)
Hardness: 7 on Mohs scale; Color: off-white to light gray/beige; Luster: dull to faintly vitreous; Texture: smooth, well-rounded water-worn pebble with fine-grained crystalline texture; Cleavage: none.
- Hardness
- 7 on Mohs scale
- Color
- off-white to light gray/beige
- Luster
- dull to faintly vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: off-white to light gray/beige; Luster: dull to faintly vitreous; Texture: smooth, well-rounded water-worn pebble with fine-grained crystalline texture; Cleavage: none.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, recrystallizing quartz grains into a dense interlocked matrix. Subsequently weathered and rounded by water transport in riverbeds or coastal environments.
Uses & applications
Commonly used as decorative river stone, landscaping gravel, aggregate in construction, and as a durable outdoor material.
Geological facts
Quartzite is so tough that when it breaks, it fractures through the quartz grains rather than around them, unlike sandstone which breaks along grain boundaries.
Field identification & locations
Identified in the field by its hardness (cannot be scratched by a steel blade), rounded water-worn shape, and sugar-like crystalline grain structure visible under close inspection. Commonly found along riverbanks, lakeshores, and glacial deposits worldwide.
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