metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: White to light grey; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6 to 2.7.
- Hardness
- 7 on Mohs scale
- Color
- White to light grey
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: White to light grey; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6 to 2.7.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure Recrystallize the quartz grains into a dense, interlocking mosaic of silica. This specific specimen is a river-worn or beach-tumbled pebble showing significant mechanical weathering.
Uses & applications
Crushed quartzite is used in construction and road building. High-purity quartzite is used in glassmaking and to produce silicon and ferrosilicon for the electronics and metallurgy industries. Tumbled stones are used in landscaping and aquariums.
Geological facts
Quartzite is so tough that it often survives intense weathering that destroys other rocks, leading to its accumulation in riverbeds and on beaches. It is harder than a steel knife and will scratch glass easily.
Field identification & locations
Identify in the field by its sugary, granular texture and its inability to be scratched by a steel blade. It will not fizz when exposed to acid (unlike marble). Commonly found in mountain ranges and glacial deposits.
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