sedimentary
Limestone Pebble
Sedimentary Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale); Color: Light grey to beige; Luster: Dull/Earthy; Structure: Microcrystalline to fine-grained; Cleavage: None/Irregular; Specific Gravity: 2.5-2.7
- Hardness
- 3-4 (Mohs scale)
- Color
- Light grey to beige
- Luster
- Dull/Earthy
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Physical properties
Hardness: 3-4 (Mohs scale); Color: Light grey to beige; Luster: Dull/Earthy; Structure: Microcrystalline to fine-grained; Cleavage: None/Irregular; Specific Gravity: 2.5-2.7
Formation & geological history
Formed by the accumulation of shell, coral, algal, and fecal debris in clear, warm, shallow marine waters. This specific specimen has been rounded and smoothed by water erosion (fluvial or beach action).
Uses & applications
Used extensively in construction as aggregate, in the manufacture of cement, as a soil conditioner in agriculture, and as a base for road construction.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. Most limestone is organic in origin, meaning it is made from the remains of once-living organisms.
Field identification & locations
Identified in the field by its softness (can be scratched by a steel nail) and its rapid effervescence (fizzing) when in contact with dilute hydrochloric acid. It is commonly found in riverbeds and coastal regions.
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