metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan (this specimen is tan/cream); Luster: vitreous to waxy; Structure: non-foliated, granular; Cleavage: none (conchoidal fracture); Specific Gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or tan (this specimen is tan/cream)
- Luster
- vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan (this specimen is tan/cream); Luster: vitreous to waxy; Structure: non-foliated, granular; Cleavage: none (conchoidal fracture); Specific Gravity: 2.6-2.7.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific rounded shape indicates secondary transport and erosion in a high-energy water environment (river or beach) occurring over thousands of years.
Uses & applications
Used in construction as crushed stone or ballast, in high-end landscaping, and as a raw material for manufacturing glass and ceramics. Small polished river stones are popular in home decor and zen gardens.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock, which is why it frequently appears as rounded pebbles in streambeds. It is often confused with marble, but unlike marble, it will not fizz when exposed to acid.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife (H=7) and its smooth, water-worn texture. Commonly found in glacial deposits and river beds worldwide. Collectors look for unique translucency or coloration.
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