mineral

Aragonite crystal cluster

Aragonite, orthorhombic calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Transparent to translucent pink-brown crystals with vitreous luster and blocky/prismatic forms; Mohs hardness 3.5–4, specific gravity about 2.94, with imperfect cleavage. The color may reflect iron, organic impurities, or surface treatment.

Identified August 21, 2026More mineral →

Explore Aragonite crystal cluster 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

Forms at low temperatures in caves, hot springs, marine sediments, and cavities in volcanic rocks; it is a metastable polymorph of calcite. Individual specimens commonly formed during the Cenozoic, though aragonite occurs throughout geologic time.

Uses & applications

Used mainly as a collector specimen, ornamental material, and minor carbonate source; attractive transparent crystals may be cut or displayed but are too soft for most jewelry.

Geological facts

Aragonite and calcite share the formula CaCO₃ but differ in crystal structure; aragonite can slowly recrystallize to calcite. This cluster’s geometry and color are consistent with aragonite, though definitive identification requires testing.

Field identification & locations

Identify by its radiating or clustered orthorhombic crystals, softness, and vigorous reaction to dilute acid; localities include Spain, Morocco, Mexico, Austria, and the Czech Republic. Avoid scratching and prolonged moisture or heat.