sedimentary

Oolitic Limestone

Oolite (Sedimentary rock composed of CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 on Mohs scale; Color: Cream, tan, or white with reddish-brown staining; Luster: Dull to earthy; Crystal structure: Trigonal (microcrystalline); Composition: Primarily calcite with iron oxide impurities.

Hardness: 3-4 on Mohs scale
Color: Cream, tan, or white with reddish-brown staining
Luster: Dull to earthy

Identified May 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in warm, shallow, agitated marine environments where calcium carbonate precipitates around a grain of sand or shell fragment (nucleus). The constant rolling in waves creates the spherical 'ooids'. This specimen shows Liesegang rings (reddish bands) from later mineral-rich fluid seepage.

Uses & applications

Used widely in construction (Portland stone), as a soil conditioner (lime), and as a flux in steel making. Higher quality specimens are used for architectural masonry and sculpture.

Geological facts

The term 'oolite' comes from the Greek word 'oion' meaning egg, because it looks like fish roe. Much of the famous architecture in Bath and London, England, is built using oolitic limestone.

Field identification & locations

Identify in the field by looking for tiny (0.25–2.0 mm) spherical grains; it will effervesce (fizz) vigorously when in contact with dilute hydrochloric acid. Commonly found in tropical marine shelf areas.