metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on the Mohs scale. Color: Tan, beige, or light brown. Luster: Dull to waxy when water-worn. Crystal structure: Hexagonal (microcrystalline). It is extremely durable and lacks cleavage.
- Hardness
- 7 on the Mohs scale
- Color
- Tan, beige, or light brown
- Luster
- Dull to waxy when water-worn
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Physical properties
Hardness: 7 on the Mohs scale. Color: Tan, beige, or light brown. Luster: Dull to waxy when water-worn. Crystal structure: Hexagonal (microcrystalline). It is extremely durable and lacks cleavage.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific specimen has been further shaped and rounded by fluvial erosion in a river or coastal environment.
Uses & applications
Used primarily as decorative landscaping stone, in road construction, and as railroad ballast. Smooth pebbles like this are also popular for use in aquariums and craft projects.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, often forming the caps of hills or ridges. It is frequently mistaken for chert, but has a more granular sugary texture under magnification.
Field identification & locations
Identified by its extreme hardness (cannot be scratched by a steel knife) and smooth, rounded appearance. Often found in riverbeds, glacial deposits, and along beaches. Collectors value them for lapidary work.
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