metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Off-white, tan, or light gray; Luster: Dull to vitreous; Structure: Granoblastic, non-foliated; Cleavage: None (conchoidal fracture); High durability.
- Hardness
- 7 on Mohs scale
- Color
- Off-white, tan, or light gray
- Luster
- Dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Off-white, tan, or light gray; Luster: Dull to vitreous; Structure: Granoblastic, non-foliated; Cleavage: None (conchoidal fracture); High durability.
Formation & geological history
Formed from the regional metamorphism of quartz sandstone (a sedimentary rock) subjected to high heat and pressure, causing quartz grains to recrystallize and fuse. Often rounded by fluvial or glacial transport.
Uses & applications
Used in construction as a sturdy aggregate, as decorative landscaping stones (river rock), and historically as a material for masonry and projectile points.
Geological facts
Quartzite is one of the most durable and weather-resistant rocks on Earth. A quartzite pebble is so hard that it can easily scratch glass or steel.
Field identification & locations
Identified in the field by its hardness (scratches glass), sugary appearance on fresh surfaces, and lack of reaction to acid. Often found in riverbeds, glacial tills, and mountainous metamorphic terrains.
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