metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 (Mohs scale); Color: Tan, beige, or yellowish due to iron oxides; Luster: Vitreous to dull; Crystal structure: Hexagonal; Cleavage: Indistinct/conchoidal fracture; Specific gravity: approx 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Tan, beige, or yellowish due to iron oxides
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: Tan, beige, or yellowish due to iron oxides; Luster: Vitreous to dull; Crystal structure: Hexagonal; Cleavage: Indistinct/conchoidal fracture; Specific gravity: approx 2.65
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize into a dense rock. This specific specimen has been rounded by water erosion (alluvial action).
Uses & applications
Used widely in construction as crushed stone, for landscaping (river rocks), and as a raw material for glass manufacturing. Smooth pebbles are popular for decorative gardens and aquariums.
Geological facts
Quartzite is harder than steel; if you try to scratch glass with it, it will leave a mark. It is one of the most durable rocks on Earth, often surviving long after surrounding softer rocks have eroded away.
Field identification & locations
Identify in the field by its hardness and granular texture that breaks through the grains rather than around them. Commonly found in riverbeds, glacial deposits, and mountain ranges.
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