sedimentary

Limestone (specifically Chalky Limestone)

Calcium Carbonate (CaCO3 / Calcite)

Hardness: 3 on Mohs scale; Color: White to light grey; Luster: Dull/Earthy; Crystal Structure: Trigonal (often microcrystalline); Cleavage: Perfect rhombohedral (rarely visible in massive form); Specific gravity: 2.7.

Hardness: 3 on Mohs scale
Color: White to light grey
Luster: Dull/Earthy

Identified February 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in marine environments from the accumulation of skeletal fragments of marine organisms such as coral, foraminifera, and mollusks over millions of years. This specimen appears to be of the Cretaceous period.

Uses & applications

Used primarily in the construction industry as a road base, aggregate for concrete, and in the production of cement. It is also used as a soil conditioner in agriculture and as a raw material for lime.

Geological facts

Limestone makes up about 10% of the total volume of all sedimentary rocks. It is the primary rock type in karst landscapes, which are famous for spectacular caves and sinkholes.

Field identification & locations

Identify in the field by its softness (can be scratched by a steel nail) and its vigorous effervescence when exposed to a drop of dilute hydrochloric acid. Commonly found in quarries, cliffs, and coastal areas.

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