mineral
Beach Pebble (Chalcedony / Chert)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 on the Mohs scale. Color: Grayish-green to pale olive, translucent to opaque. Luster: Waxy to vitreous when wet or smooth. Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.65.
- Hardness
- 6
- Color
- Grayish-green to pale olive, translucent to opaque
- Luster
- Waxy to vitreous when wet or smooth
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Physical properties
Hardness: 6.5-7 on the Mohs scale. Color: Grayish-green to pale olive, translucent to opaque. Luster: Waxy to vitreous when wet or smooth. Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.65.
Formation & geological history
Formed by precipitation of silica-rich fluids in sedimentary environment cavities or volcanic rock fractures, then naturally rounded and smoothed by ocean wave action over thousands to millions of years.
Uses & applications
Used primarily as decorative garden stone, landscaping pebbles, tumbling material for rockhounds, or craft items.
Geological facts
Beach pebbles made of microcrystalline quartz like chert or chalcedony are extremely durable and can survive high-energy coastal wave tumbling that breaks down softer rocks.
Field identification & locations
Identify in the field by its smooth, water-worn shape, waxy luster, and high hardness (will scratch steel or glass). Commonly found along rocky coastlines and gravel beaches.
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