mineral

Aragonite / Calcite Geode

Calcium Carbonate (CaCO3)

Hardness: 3-4 (Mohs scale), Color: Colorless to white/pale yellow with orange-brown iron staining, Luster: Vitreous to pearly, Crystal structure: Orthorhombic or Trigonal, Cleavage: Perfect rhombohedral

Identified April 20, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the precipitation of calcium-rich groundwater in sedimentary cavities or volcanic rock voids. This piece appears to be a smaller vug or geode portion often found in desert environments.

Uses & applications

Primarily used for geological collecting, decorative display, and metaphysical purposes. Industrial uses of calcium carbonate include cement production and agricultural lime.

Geological facts

Aragonite and Calcite are polymorphs; they share the same chemical formula but have different crystal structures. Over long geological time scales, aragonite often converts into calcite.

Field identification & locations

Identify in the field by its crystal habit and a positive reaction (fizzing) when exposed to a drop of weak acid (dilute HCl or vinegar). Often found in limestone caves or weathered sedimentary outcrops.

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Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral