mineral
Quartz Geode with Calcite/Siderite
Crystalline Silicon Dioxide (SiO2) with Carbonate inclusions
Hardness: 7 (Quartz shell), Color: White to tan/brown center, Luster: Vitreous to dull, Crystal structure: Hexagonal/Trigonal, Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Quartz shell), Color: White to tan/brown center, Luster: Vitreous to dull, Crystal structure: Hexagonal/Trigonal, Specific Gravity: 2.65
Formation & geological history
Formed in cavities of sedimentary or volcanic rocks where mineral-rich groundwater precipitates crystals over thousands of years. Often found in limestone or shale beds.
Uses & applications
Decorative display, metaphysical collecting, educational specimens, and lapidary art.
Geological facts
Geodes are geological secondary structures which occur in certain sedimentary and volcanic rocks. They are essentially rock cavities or vugs with internal crystal formations.
Field identification & locations
Identify by the characteristic hollow center surrounded by a crystalline wall. Common in the Midwest USA (Keokuk region), Brazil, and Morocco. Look for rounded nodules that feel lighter than solid rocks.
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