mineral

Quartz Geode with Calcite

Silicon Dioxide (SiO2) with Calcium Carbonate (CaCO3)

Hardness: 7 (Quartz) and 3 (Calcite); Color: Tan, white, clear, to yellowish; Luster: Vitreous to pearly; Crystal structure: Hexagonal/trigonal and rhombohedral; Cleavage: None (Quartz) to perfect rhombohedral (Calcite).

Hardness: 7 (Quartz) and 3 (Calcite)
Color: Tan, white, clear, to yellowish
Luster: Vitreous to pearly

Identified June 20, 2026More mineral →

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Physical properties

Formation & geological history

Geodes form in cavities of sedimentary or volcanic rocks. Mineral-rich water seeps into these hollows, precipitating crystals over millions of years. This specimen appears to be of the sedimentary variety often found in limestone or shale beds.

Uses & applications

Mainly used for educational purposes, mineral collecting, home decor, and spiritual/metaphysical practices. Calcite and quartz minerals are also used industrially in glass making and optics.

Geological facts

The word 'geode' comes from the Greek word 'geodes', meaning earth-like. Unlike a vug, which is a cavity in rock, a geode is a separate structure that can be removed from its host rock as a single piece.

Field identification & locations

Identify by the rough, stone-like exterior and the hollow interior lined with sparkling crystals. Often found in dry, desert areas or riverbeds where limestone is present. Can be tested with diluted hydrochloric acid; the calcite part will fizz.

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