sedimentary

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Hardness: 3 (Mohs scale); Color: Gray to tan matrix with white fossil inclusions; Luster: Dull/earthy matrix, vitreous fossils; Structure: Sedimentary bedding with visible bioclasts; Cleavage: None (conchoidal to irregular fracture).

Hardness: 3 (Mohs scale)
Color: Gray to tan matrix with white fossil inclusions
Luster: Dull/earthy matrix, vitreous fossils

Identified June 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow, warm marine environments through the accumulation of shell, coral, algal, and fecal debris. Over millions of years, these calcium carbonate remains are lithified into solid rock. These specific patterns likely date from the Paleozoic or Mesozoic eras.

Uses & applications

Limestone is used extensively in construction as building stone, in the manufacturing of cement (Portland cement), as a soil conditioner in agriculture, and as a decorative stone in landscaping.

Geological facts

The white patterns in this specimen are cross-sections of ancient marine organisms, possibly shells or crinoid fragments. Limestone makes up about 10% of the total volume of all sedimentary rocks on Earth.

Field identification & locations

Identified by its reaction to dilute hydrochloric acid (it will fizz) and the presence of visible fossils. Common in areas that were once prehistoric sea beds. Check for preservation quality of the fossil outlines.

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