sedimentary

Fossiliferous Limestone

Calcium carbonate (CaCO3) with marine fossils

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Grey, tan, or white; Luster: Dull to earthy; Crystal structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral in calcite crystals; Specific gravity: 2.7.

Hardness: 3 on Mohs scale
Color: Grey, tan, or white
Luster: Dull to earthy

Identified June 3, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Grey, tan, or white; Luster: Dull to earthy; Crystal structure: Trigonal (as calcite); Cleavage: Perfect rhombohedral in calcite crystals; Specific gravity: 2.7.

Formation & geological history

Formed in warm, shallow marine environments through the accumulation of shell, coral, algal, and fecal debris over millions of years (Paleozoic to Cenozoic eras).

Uses & applications

Used in construction as a building material, aggregate for roads, production of cement/lime, and by collectors for the fossils it contains.

Geological facts

The Great Pyramids of Giza are mostly constructed from fossiliferous limestone. This specific specimen contains visible remnants of ancient marine organisms like crinoids or bryozoans.

Field identification & locations

Identify in the field by looking for visible shell fragments or fossils. It will react and fizz (effervesce) when a drop of cold dilute hydrochloric acid (or vinegar) is applied.