metamorphic
Quartzite Pebble
SiO2 (Silicon Dioxide)
Hardness: 7 on Mohs scale; Color: light grey to white; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none, breaks with a conchoidal or irregular fracture.
- Hardness
- 7 on Mohs scale
- Color
- light grey to white
- Luster
- vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: light grey to white; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none, breaks with a conchoidal or irregular fracture.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under extreme heat and pressure. The original sandstone grains recrystallize to form an interlocking network of quartz crystals. This specimen appears water-worn into a pebble shape.
Uses & applications
Raw quartzite is used in construction as crushed stone or ballast. In smaller, rounded forms like this, it is common in landscaping or as a collectible beach/river stone. High-purity quartzite is used to produce glass and silicon.
Geological facts
Quartzite is so tough that it often survives intense weathering that destroys other rocks. It is harder than steel and will easily scratch glass. Many quartzite formations are hundreds of millions to billions of years old.
Field identification & locations
Look for a sugary, crystalline texture and extreme hardness (cannot be scratched by a steel knife). Common in riverbeds, glacial deposits, and mountain ranges. Collectors find them as easy-to-identify examples of metamorphic processes.
