page_title: Geode
hierarchical_section_title: Geode
caption_attribution_description: Nederlands: Geode amethist In het kader van &quot;Wiki loves art NL&quot;.
context_page_description: Geodes are geological secondary formations within sedimentary and volcanic rocks. Geodes are hollow, vaguely spherical rocks, in which masses of mineral matter are secluded. The crystals are formed by the filling of vesicles in volcanic and sub-volcanic rocks by minerals deposited from hydrothermal fluids; or by the dissolution of syn-genetic concretions and partial filling by the same, or other, minerals precipitated from water, groundwater or hydrothermal fluids.
context_section_description: Geodes (derived from the Greek word "γεώδης" meaning "Earth-like") are geological secondary formations within sedimentary and volcanic rocks. Geodes are hollow, vaguely spherical rocks, in which masses of mineral matter (which may include crystals) are secluded. The crystals are formed by the filling of vesicles in volcanic and sub-volcanic rocks by minerals deposited from hydrothermal fluids; or by the dissolution of syn-genetic concretions and partial filling by the same, or other, minerals precipitated from water, groundwater or hydrothermal fluids.  
caption: The inside of a large geode lined by amethyst crystals
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