sedimentary
Limestone (River Stone)
Calcium Carbonate (CaCO3)
Hardness: 3-4 (Mohs scale), Color: Creamy white to light gray, Luster: Dull/Earthy, Crystal Structure: Microcrystalline, Cleavage: None/Conchoidal, Specific Gravity: 2.5-2.7
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Physical properties
Hardness: 3-4 (Mohs scale), Color: Creamy white to light gray, Luster: Dull/Earthy, Crystal Structure: Microcrystalline, Cleavage: None/Conchoidal, Specific Gravity: 2.5-2.7
Formation & geological history
Formed through the accumulation of shell, coral, algal, and fecal debris in warm, shallow marine waters. This specific specimen has been rounded and smoothed by fluvial (river) or glacial transport processes.
Uses & applications
Raw material for cement, crushed stone for road construction, lime for soil treatment, and occasionally used in landscaping or as carving stone.
Geological facts
Limestone makes up about 10% of the total volume of all sedimentary rocks. It is highly susceptible to acid rain, which can dissolve the rock over long periods of time, leading to karst landscapes.
Field identification & locations
Identify in the field by its softness (can be scratched by a steel nail) and its reaction to dilute hydrochloric acid (it will fizz/effervesce). This pear-shaped specimen is typical of stones smoothed by long-term water erosion.
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