sedimentary

Likely fossil-bearing limestone fragment

Limestone, chiefly calcite (CaCO₃); exact identification is uncertain from the image

AI-generated identification · may be incorrect

Cream-colored, rounded and worn, with a small angular dark cavity or inclusion. Limestone is typically Mohs 3, nonmetallic with a dull to slightly sugary luster, and composed mainly of microcrystalline calcite; crystal structure is trigonal.

Identified October 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when carbonate mud, shells, or skeletal debris accumulate and lithify in marine or lake settings. Its age and whether the visible feature is a fossil cannot be determined from the photograph.

Uses & applications

Limestone is widely used for cement, lime, aggregate, and building stone; this small fragment has little practical value beyond collecting or teaching.

Geological facts

Calcite-rich limestone effervesces when a drop of dilute acid is applied; avoid testing if the specimen may be valuable or fragile.

Field identification & locations

Look for a scratchable surface and acid fizz; the cavity could be a fossil fragment or an ordinary break, so inspect with magnification. Limestone occurs worldwide in sedimentary basins.