sedimentary

Calcite-rich limestone (possibly fossiliferous limestone)

Calcite, CaCO₃, in a limestone matrix

AI-generated identification · may be incorrect

Creamy white, translucent to opaque material with a sugary/earthy tan coating and curved cleavage-like surfaces. Calcite has Mohs hardness 3, vitreous to pearly luster, rhombohedral cleavage, and specific gravity about 2.71; it fizzes with dilute hydrochloric acid.

Identified August 8, 2026More sedimentary →

Explore Calcite-rich limestone (possibly fossiliferous limestone) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Likely formed as carbonate sediment or biogenic shell material that lithified into limestone, with later weathering exposing the pale calcite-rich interior. Precise age and identification cannot be determined from the photograph.

Uses & applications

Used for cement, agricultural lime, building stone, and aggregate; attractive translucent pieces may be collected or polished, though this specimen appears mainly geological rather than gem-grade.

Geological facts

The pale interior could also be a weathered shell or calcite-filled cavity; a close look at texture and acid reaction would distinguish these possibilities.

Field identification & locations

Common in limestone terrains worldwide. Test with a steel nail, vinegar or dilute HCl, and inspect for shell layering or rhombohedral cleavage; vinegar may react weakly. The note “kimaha” provides no diagnostic contradiction.