metamorphic and sedimentary
Quartzite and Sandstone Pebbles
Silicon dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Off-white, light gray, beige; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Off-white, light gray, beige
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Off-white, light gray, beige; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None/Conchoidal fracture; Specific gravity: 2.65
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone (quartzite) or the lithification and rounding of sand grains in river or beach environments. Common in ancient sedimentary basins globally.
Uses & applications
Construction aggregate, glass making raw material, flintknapping for primitive tools, and aquarium decor.
Geological facts
Quartzite is one of the most durable rocks on Earth, surviving long-term erosion that destroys other minerals. Sandstone makes up about 10-20% of Earth's sedimentary rock record.
Field identification & locations
Identify by its ability to scratch glass and lack of reaction to acid. Often found in riverbeds, glacial deposits, and beaches. Collectors focus on unique shapes or colors.
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