mineral

Aragonite Star Cluster

Aragonite (CaCO3)

Hardness: 3.5-4 (Mohs); Color: Brown, orange, or white; Luster: Vitreous to resinous; Crystal structure: Orthorhombic (often forming pseudo-hexagonal twinned crystals); Cleavage: Distinct in one direction; Specific gravity: 2.9-3.0

Hardness: 3
Color: Brown, orange, or white
Luster: Vitreous to resinous

Identified June 28, 2026More mineral →

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Physical properties

Formation & geological history

Forms in low-temperature hydrothermal environments or as a secondary mineral in oxidized zones of ore deposits. These clusters often form in sedimentary clays or marls through evaporation and precipitation.

Uses & applications

Primarily used as decorative display specimens for mineral collectors and in jewelry as beads or cabochons. Historically used in cement and as a source of lime.

Geological facts

Aragonite is a polymorph of calcium carbonate, meaning it has the same chemical formula as calcite but a different crystal structure. It is also the primary component of many sea shells and pearls.

Field identification & locations

Identify in the field by its distinct 'starburst' or 'satellite' crystal habit. Commonly found in Morocco (specifically the Tazouta region), Spain, and the United Kingdom.