metamorphic
Quartzite Pebble
Quartzite (composed primarily of Silica, SiO2)
Hardness: 7 on Mohs scale; Color: White to light tan; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65
- Hardness
- 7 on Mohs scale
- Color
- White to light tan
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: White to light tan; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65
Formation & geological history
Quartzite forms from the metamorphism of quartz sandstone. High heat and pressure reciprocal to tectonic compression cause the sand grains to recrystallize and fuse together. It can be found in mountain belts globally.
Uses & applications
Used in construction as crushed stone for road beds, in the chemical industry as a source of silica, and as decorative landscaping stones or river rock.
Geological facts
Quartzite is so hard and dense that when it breaks, it fractures through the sand grains rather than around them, unlike its parent rock sandstone.
Field identification & locations
Identified in the field by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Often found as rounded pebbles in riverbeds or glacial deposits due to its durability.
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