mineral

Aragonite Star Cluster

Aragonite (Calcium Carbonate, CaCO3)

Hardness: 3.5-4 (Mohs); Color: Honey-brown, orange-red, or amber; Luster: Vitreous to resinous; Crystal Structure: Orthorhombic; Cleavage: Distinct in one direction; Specific Gravity: 2.94

Hardness: 3
Color: Honey-brown, orange-red, or amber
Luster: Vitreous to resinous

Identified April 5, 2026More mineral →

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Physical properties

Hardness: 3.5-4 (Mohs); Color: Honey-brown, orange-red, or amber; Luster: Vitreous to resinous; Crystal Structure: Orthorhombic; Cleavage: Distinct in one direction; Specific Gravity: 2.94

Formation & geological history

Formed through biological and physical processes, often in marine environments, caves (as stalactites), or hot springs. These 'star' clusters typically form in sedimentary environments through precipitation from calcium-rich solutions.

Uses & applications

Primarily used as decorative display pieces and collected by mineral enthusiasts. In industry, aragonite is used in cement, livestock feed, and soil conditioners, and it plays a vital role in the health of marine aquariums.

Geological facts

Aragonite is a polymorph of calcite, meaning they have the same chemical formula but different crystal structures. It is the primary mineral used by mollusks and corals to build their shells and skeletons.

Field identification & locations

Identify in the field by its pseudo-hexagonal twinning that creates a 'sputnik' or star-like shape. It will effervesce (fizz) intensely when in contact with dilute hydrochloric acid. Commonly found in Morocco, Spain, and the Southwestern USA.

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