sedimentary

Quartz Geode

Quartz (Silicon Dioxide, SiO2) Geode

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: Grayish-white to clear interior, dark green to gray rind; Luster: Vitreous/Glassy; Structure: Hexagonal crystals; Cleavage: None (conchoidal fracture).

Hardness: 7 (Mohs scale)
Color: Grayish-white to clear interior, dark green to gray rind
Luster: Vitreous/Glassy

Identified March 18, 2026More sedimentary →

Explore Quartz Geode in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 7 (Mohs scale); Color: Grayish-white to clear interior, dark green to gray rind; Luster: Vitreous/Glassy; Structure: Hexagonal crystals; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed as secondary fillings in hollow cavities within sedimentary rocks or volcanic ash. Silica-rich groundwater precipitates crystals over millions of years. This specimen appears typical of those found in limestone formations.

Uses & applications

Aesthetic decoration, lapidary arts, metaphysical use, and as a popular educational specimen for mineral collectors.

Geological facts

Geodes are often referred to as 'thunder eggs' when filled solid. While they appear like ordinary rocks on the exterior, they contain hollow cavities lined with inward-growing crystals.

Field identification & locations

Identify in the field by their rounded, bumpy exterior and unusual lightness for their size. This specific specimen shows a 'druzy' quartz layer on a darker chalcedony/limestone base. Commonly found in Morocco or the American Midwest.