geode

American  

[jee-ohd] / ˈdʒi oʊd /

noun

1. a hollow concretionary or nodular stone often lined with crystals.

2. the hollow or cavity of this.

3. any similar formation.

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geode British  

/ dʒɪˈɒdɪk, ˈdʒiːəʊd /

noun

1. a cavity, usually lined with crystals, within a rock mass or nodule

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geode Scientific  

/ jē′ōd′ /

1. A small, hollow, usually rounded rock lined on the inside with inward-pointing crystals. Geodes form when mineral-rich water entering a cavity in a rock undergoes a sudden change in pressure or temperature, causing crystals to form from the solution and line the cavity's walls.

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Other Word Forms

• geodal adjective
• geodic adjective

Etymology

Origin of geode

1670–80; < French géode < Latin geōdēs < Greek geṓdēs earthlike. See geo-, -ode ¹