sedimentary
River Stone (Limestone)
Sedimentary Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale); Color: tan, grey, beige; Luster: dull to earthy; Texture: smooth, water-worn; Cleavage: none visible in pebble form; Specific gravity: 2.3-2.7
- Hardness
- 3-4 (Mohs scale)
- Color
- tan, grey, beige
- Luster
- dull to earthy
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Physical properties
Hardness: 3-4 (Mohs scale); Color: tan, grey, beige; Luster: dull to earthy; Texture: smooth, water-worn; Cleavage: none visible in pebble form; Specific gravity: 2.3-2.7
Formation & geological history
Formed through the accumulation of organic debris such as shells or chemical precipitation in marine environments. This specimen was subsequently smoothed and rounded by the abrasive action of water (river or beach) over many years.
Uses & applications
Commonly used as decorative landscaping stones, aquarium substrate, or as a natural 'worry stone' for tactile comfort. Industrial limestone is used in cement production.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. Many river stones like this one contain microscopic fragments of ancient marine life.
Field identification & locations
Identified by its rounded shapes, matte finish, and reaction to acids (bubbles with vinegar). Found worldwide in riverbeds, beaches, and glacial deposits.
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