sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 on Mohs scale; Color: Tan, buff, gray, orange-brown; Luster: Dull/Earthy; Crystal Structure: Trigonal (as calcite); Cleavage: Rhombohedral (in mineral form).
- Hardness
- 3 on Mohs scale
- Color
- Tan, buff, gray, orange-brown
- Luster
- Dull/Earthy
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Physical properties
Hardness: 3 on Mohs scale; Color: Tan, buff, gray, orange-brown; Luster: Dull/Earthy; Crystal Structure: Trigonal (as calcite); Cleavage: Rhombohedral (in mineral form).
Formation & geological history
Formed primarily from the accumulation of skeletal fragments of marine organisms such as coral, foraminifera, and mollusks in shallow marine environments over millions of years.
Uses & applications
Used extensively in construction (road base, concrete), agriculture (soil conditioner), industrial manufacturing (steel production), and architecture.
Geological facts
Limestone accounts for about 10% of the total volume of all sedimentary rocks on Earth. It is the primary parent rock for caves and karst topography because it is soluble in rainwater.
Field identification & locations
Identify in the field by its reaction to dilute hydrochloric acid (it will fizz). Look for fossil remains and a fine-grained, earthy texture. Common in ancient reef areas and basin regions.
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