mineral
Aragonite Star Cluster
Aragonite (Calcium Carbonate, CaCO3)
Hardness: 3.5-4.0; Color: Honey-orange to reddish-brown; Luster: Vitreous to resinous; Crystal Structure: Orthorhombic (often forming hexagonal-looking pseudohexagonal twins); Specific Gravity: 2.95
- Hardness
- 3
- Color
- Honey-orange to reddish-brown
- Luster
- Vitreous to resinous
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Physical properties
Hardness: 3.5-4.0; Color: Honey-orange to reddish-brown; Luster: Vitreous to resinous; Crystal Structure: Orthorhombic (often forming hexagonal-looking pseudohexagonal twins); Specific Gravity: 2.95
Formation & geological history
Formed in low-temperature near-surface environments, often as an authigenic mineral in sedimentary rocks or through precipitation in hot springs and caves, typically within the last few million years.
Uses & applications
Primarily used as a decorative mineral specimen for collectors, sometimes used in metaphysical practices, and historically as a minor source of lime.
Geological facts
Aragonite is a polymorph of Calcite, meaning they share the same chemistry but different crystal structures. It is also the primary constituent of mother-of-pearl (nacre) in mollusk shells.
Field identification & locations
Identified by its distinctive twinned, radiating hexagonal prisms (star clusters) and its reaction (fizzing) with weak hydrochloric acid. Famous specimens come from Tazouta, Morocco.
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