sedimentary
Fossiliferous Limestone
Carbonate sedimentary rock (CaCO3)
Hardness: 3-4 (Mohs scale), Color: Gray/beige/tan, Luster: Dull to earthy, Crystal Structure: Trigonal (microcrystalline calcite), Cleavage: Perfect rhombohedral in calcite crystals but often invisible in bulk rock.
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Physical properties
Hardness: 3-4 (Mohs scale), Color: Gray/beige/tan, Luster: Dull to earthy, Crystal Structure: Trigonal (microcrystalline calcite), Cleavage: Perfect rhombohedral in calcite crystals but often invisible in bulk rock.
Formation & geological history
Formed in marine environments through the accumulation of shell, coral, algal, and fecal debris. Primarily associated with shallow tropical or subtropical seas throughout various geological ages (Paleozoic to modern).
Uses & applications
Used extensively in construction (aggregate, cement, building stones), as a soil conditioner in agriculture, and small fossiliferous pieces are popular in educational collections.
Geological facts
Limestone accounts for about 10% of the total volume of all sedimentary rocks. Many specimens contain visible ancient sea creatures like crinoids, shells, or coral fragments.
Field identification & locations
Identify by looking for visible fossil imprints or shell fragments; reacts with a fizzing sound when a drop of dilute hydrochloric acid (or vinegar) is applied. Found worldwide in former sea beds.
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