sedimentary
Limestone
Sedimentary Rock (Calcium Carbonate, CaCO3)
Hardness: 3 on Mohs scale; Color: Grey to buff with patches of green moss/algae; Luster: Dull/earthy; Crystal Structure: Microcrystalline; Cleavage: None/conchoidal; Specific Gravity: 2.5-2.7.
- Hardness
- 3 on Mohs scale
- Color
- Grey to buff with patches of green moss/algae
- Luster
- Dull/earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Grey to buff with patches of green moss/algae; Luster: Dull/earthy; Crystal Structure: Microcrystalline; Cleavage: None/conchoidal; Specific Gravity: 2.5-2.7.
Formation & geological history
Formed primarily from the accumulation of shell, coral, algal, and fecal debris in warm, shallow marine waters. The specimen's reported location in North-Central Ohio (Marion/Morrow county area) is consistent with the Devonian or Silurian aged carbonate bedrock prevalent in that region.
Uses & applications
Extensively used as an aggregate for road base, railroad ballast, and in the production of cement and lime. Also used as a soil conditioner in agriculture to neutralize acidity.
Geological facts
Limestone is the primary source of the world's lime and is crucial for the manufacture of steel and glass. Many limestones contain fossils of ancient marine life like crinoids or brachiopods.
Field identification & locations
Identify in the field by its grey color and its tendency to 'fizz' (effervesce) when a drop of diluted hydrochloric acid or strong vinegar is applied. Commonly found in quarries and outcrops throughout the Ohio River Valley.
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