sedimentary

Limestone

Calcite-dominated limestone (CaCO₃), possibly impure or fossiliferous limestone

AI-generated identification · may be incorrect

Typically gray to cream, dull to earthy, fine- to coarse-grained, and relatively soft (Mohs 3). Calcite commonly shows weak cleavage; it effervesces strongly with dilute hydrochloric acid or vinegar, though weathered surfaces may react slowly. Specific gravity is about 2.3–2.7.

Identified September 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms mainly from accumulated marine carbonate mud, shells, and skeletal debris, later compacted and cemented. These specimens are consistent with young tropical sedimentary rocks of South Kalimantan, commonly Cretaceous–Neogene in regional carbonate sequences, though exact age requires mapping or laboratory analysis.

Uses & applications

Used for cement and lime manufacture, aggregate, road base, construction stone, soil treatment, and industrial calcium carbonate. Attractive varieties may be cut or polished, but these appear mainly as mining specimens.

Geological facts

The user’s “batu kapur” description and the pale, massive appearance strongly support limestone. Some pieces may contain recrystallized calcite or dolomite, which can reduce acid reaction.

Field identification & locations

Common in karst and carbonate-bearing areas of South Kalimantan, including mining districts. Identify by its low hardness, pale color, sedimentary texture, and acid fizz; a scratch test and acid test are useful, but avoid damaging display pieces.