metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale); Color: Tan/light brown; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None, conchoidal fracture; Specific gravity: approx 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Tan/light brown
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: Tan/light brown; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None, conchoidal fracture; Specific gravity: approx 2.65
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, typically during tectonic plate collisions. This specific specimen has been further shaped and smoothed by water erosion through fluvial or coastal processes.
Uses & applications
Used in construction as crushed stone or ballast. Rounded pebbles are popular in landscaping, aquariums, and decorative garden paths. High-purity quartzite is a source of silica for glass and metal smelting.
Geological facts
Quartzite is so hard that it will scratch glass. In many mountain ranges, quartzite forms the most prominent peaks and ridges because it is extremely resistant to chemical and physical weathering.
Field identification & locations
Identify by its hardness (will scratch a steel knife) and its grainy, sugary texture when viewed closely. Common in riverbeds, glacial tills, and beaches worldwide. Collectors look for unique colors or translucent qualities.
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