mineral

Aragonite Star Cluster

Aragonite (Calcium Carbonate, CaCO3)

Hardness: 3.5-4 (Mohs scale); Color: reddish-brown or honey; Luster: Vitreous to resinous; Crystal structure: Orthorhombic (often forming pseudo-hexagonal twinned crystals); Specific gravity: 2.9-3.0.

Hardness: 3
Color: reddish-brown or honey
Luster: Vitreous to resinous

Identified June 3, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily through sedimentary processes in oxidation zones of ore deposits, caves, or hot springs. These characteristic 'star' clusters are typically from the Tazouta mine in Morocco, formed by cyclic twinning of crystals.

Uses & applications

Primarily popular as a display cabinet specimen for mineral collectors. Some lower grade material is used for ornamental carvings or as a source of calcium, but it is too soft for most jewelry.

Geological facts

Aragonite is chemically identical to Calcite but has a different crystal structure, making them polymorphs. Over long geological time, aragonite often reverts to the more stable calcite form.

Field identification & locations

Identified by its standard pseudo-hexagonal twinned prisms and distinctive reddish-brown color. Found commonly in Morocco, Spain, and Mexico. Collectors should avoid cleaning with acid as it will dissolve.

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