sedimentary
Limestone
Calcium Carbonate (CaCO3)
Hardness: 3 (Mohs scale), Color: Gray to light tan, Luster: Dull to earthy, Crystal Structure: Hexagonal (Scalenohedral) as Calcite, Cleavage: Perfect rhombohedral
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Physical properties
Hardness: 3 (Mohs scale), Color: Gray to light tan, Luster: Dull to earthy, Crystal Structure: Hexagonal (Scalenohedral) as Calcite, Cleavage: Perfect rhombohedral
Formation & geological history
Formed primarily in shallow marine waters by the accumulation of shell, coral, algal, and fecal debris. It can also form through chemical precipitation from lake or ocean water.
Uses & applications
Extensively used in construction as an aggregate for concrete and asphalt, used in the manufacture of cement, and as a flux in steel production.
Geological facts
Limestone is the primary source of lime and makes up about 10% of the total volume of all sedimentary rocks. It is essential for the formation of cave systems and karst topography.
Field identification & locations
Can be identified in the field by its reaction to dilute hydrochloric acid (it fizzes). Common in regions that were once ancient sea beds. Check for fossil inclusions.
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