mineral

Aragonite

Aragonite (Carbonate mineral), CaCO3

Hardness: 3.5-4.0 (Mohs scale), Color: White, pinkish, or colorless, Luster: Vitreous to resinous, Crystal system: Orthorhombic, Cleavage: Distinct in one direction, Specific Gravity: 2.94

Hardness: 3

Identified April 6, 2026More mineral →

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Physical properties

Hardness: 3.5-4.0 (Mohs scale), Color: White, pinkish, or colorless, Luster: Vitreous to resinous, Crystal system: Orthorhombic, Cleavage: Distinct in one direction, Specific Gravity: 2.94

Formation & geological history

Formed at low temperatures near the Earth's surface through precipitation from marine and freshwater environments, or in caves as stalactites. It is also found in hydrothermal veins and hot springs. It is a polymorph of Calcite.

Uses & applications

Used primarily as collector specimens, in some jewelry as beads/carvings, and historically as a source of lime. In the marine industry, it is used for maintaining PH balance in aquariums.

Geological facts

Aragonite is the primary component of the shells of many marine organisms like mollusks and corals. Over geological time, aragonite is unstable at standard surface temperatures and pressures and often converts to calcite.

Field identification & locations

Identify in the field by its effervescence (fizzing) in weak acid and its pseudo-hexagonal twinning or acicular (needle-like) crystal habits. Commonly found in Morocco, Namibia, Spain, and Mexico.