mineral

Quartz Geode

Crystalline Silicon Dioxide (SiO2) in sedimentary/volcanic host

Hardness: 7 (Mohs scale), Color: Colorless to white, Luster: Vitreous/glassy, Structure: Trigonal (hexagonal prisms), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified May 30, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Colorless to white, Luster: Vitreous/glassy, Structure: Trigonal (hexagonal prisms), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Formed when minerals precipitate from groundwater into hollow cavities (gas bubbles or decayed organic matter) within volcanic or sedimentary rocks over thousands to millions of years.

Uses & applications

Primarily used for geological display, home decor, holistic healing practices, and as educational specimens for geology students.

Geological facts

Geodes are like nature's 'surprise eggs'; while they look like ordinary rocks on the outside, they contain beautiful crystal hollows. The word geode comes from the Greek 'geoides' meaning earth-like.

Field identification & locations

Identify by looking for rounded, hollow nodules that feel lighter than they appear. In the field, crack them open to reveal internal crystals. Common locations include Morocco, Brazil, and the Midwestern USA (Keokuk region).

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral