mineral

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Hardness 7 on Mohs scale; white to pinkish crystalline interior surrounded by a dark brownish-gray chalcedony or basalt shell; vitreous luster inside crystals; trigonal crystal system; no cleavage.

Identified July 25, 2026More mineral →

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Physical properties

Hardness 7 on Mohs scale; white to pinkish crystalline interior surrounded by a dark brownish-gray chalcedony or basalt shell; vitreous luster inside crystals; trigonal crystal system; no cleavage.

Formation & geological history

Formed in cavities within volcanic or sedimentary rocks where mineral-rich water precipitates quartz crystals inward over long periods.

Uses & applications

Used primarily as decorative mineral specimens, in jewelry, or for lapidary work and mineral collecting.

Geological facts

Geodes appear as ordinary, unremarkable round rocks on the outside, but breaking them open reveals a hollow cavity lined with sparkling mineral crystals.

Field identification & locations

Identify by its bumpy round exterior combined with a crystalline, hollow or solid quartz interior; widely found in volcanic ash beds and limestone formations.