mineral

Aragonite Star Cluster

Aragonite (CaCO3)

Hardness: 3.5-4 on Mohs scale; Color: Reddish-brown, honey-yellow, or white; Luster: Vitreous to resinous; Crystal Structure: Orthorhombic (often forming pseudo-hexagonal twinned crystals); Specific Gravity: 2.95.

Hardness: 3
Color: Reddish-brown, honey-yellow, or white
Luster: Vitreous to resinous

Identified May 30, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through low-temperature sedimentary processes, such as precipitation from hot springs or in caves as speleothems. This specific 'star' habit often comes from oxidized zones of deposits.

Uses & applications

Primarily used as decorative collector specimens, metaphysical healing stones, and occasionally in the manufacturing of cement or as a calcium supplement.

Geological facts

Aragonite is chemically identical to calcite (polymorphs), but they have different crystal structures. It is also the primary material found in mother-of-pearl and pearls.

Field identification & locations

Identified by its unique 'sputnik' or star-burst hexagonal twinned crystal habit and its reaction (fizzing) to cold dilute hydrochloric acid. Commonly found in Morocco, Spain, and Mexico.