mineral

Aragonite Star Cluster

Aragonite (Calcium Carbonate, CaCO3)

Hardness: 3.5-4 on Mohs scale; Color: Reddish-brown, tan, or colorless; Luster: Vitreous to resinous; Crystal structure: Orthorhombic (cyclic twinning forms pseudo-hexagonal prisms); Cleavage: Distinct; Specific gravity: 2.95

Hardness: 3
Color: Reddish-brown, tan, or colorless
Luster: Vitreous to resinous

Identified May 30, 2026More mineral →

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Physical properties

Formation & geological history

Formed through low-temperature sedimentary processes, typically in marine environments, hot springs, or as precipitates in caves (stalactites). These 'sputnik' clusters specifically form in clay-rich soils via evaporative processes.

Uses & applications

Primarily used as decorative display specimens for collectors and in metaphysical practices. Industrially, it is used in cement, soil pH balancing, and as a source of lime.

Geological facts

Aragonite is chemically identical to calcite but has a different crystal structure, making them polymorphs. It is also the primary material found in the shells of mollusks and pearls.

Field identification & locations

Identified by its unique 'sputnik' or starburst shape with radiating hexagonal-looking prisms. It will fizz strongly when in contact with dilute hydrochloric acid. Most commercial star clusters come from Morocco.

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