mineral

Quartz Geode

Silicon Dioxide (SiO2) - Crystalline Quartz

Hardness: 7 on Mohs scale; Color: White to translucent tan with brownish outer rind; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: White to translucent tan with brownish outer rind
Luster: Vitreous to dull

Identified May 28, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed as secondary minerals in hollow cavities (vugs) within igneous or sedimentary rocks. Silica-rich groundwater precipitates crystals over thousands of years.

Uses & applications

Primarily used as decorative specimens, for educational purposes, in rock collections, and occasionally as minor semi-precious gemstones.

Geological facts

Geodes are virtually indestructible by weather because the silica outer shell is much harder than the host rock that once surrounded them; they are often found as loose nodules in stream beds or desert soil.

Field identification & locations

Identify by its rounded, cauliflower-like exterior texture and internal crystal growth. Commonly found in limestone or volcanic ash beds in regions like the American Midwest or Brazil.

Other mineral specimens

See all

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