sedimentary
Fossiliferous Limestone
Carbonate sedimentary rock with trace fossils (CaCO3)
Hardness: 3 (Mohs scale), Color: light grey to tan, Luster: dull/earthy, Structure: biogenic/fragmental with visible shell impressions and pore space, Specific Gravity: 2.3-2.7.
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Physical properties
Hardness: 3 (Mohs scale), Color: light grey to tan, Luster: dull/earthy, Structure: biogenic/fragmental with visible shell impressions and pore space, Specific Gravity: 2.3-2.7.
Formation & geological history
Formed in shallow, calm marine environments where the accumulation of organic debris such as shell fragments and coral skeletons compressed over millions of years. This specimen shows a porous, fossil-rich texture common in Cretaceous to Pleistocene deposits.
Uses & applications
Used extensively in the aggregate industry for road construction, cement manufacturing, and building facades. In smaller pieces, it is a common classroom tool for teaching paleontology.
Geological facts
Many of the world's most famous caves are formed in limestone when acidic water dissolves the rock. This specific specimen appears to contain molds and casts of ancient marine bivalves or crinoids.
Field identification & locations
Identify in the field by its reaction to dilute hydrochloric acid (it will fizz) and the presence of visible marine fossils. It is commonly found in areas that were once prehistoric seafloors.
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