mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: Clear to milky white, Luster: Vitreous/Glassy, Crystal Structure: Hexagonal (Trigonal), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.65

Identified April 4, 2026More mineral →

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: Clear to milky white, Luster: Vitreous/Glassy, Crystal Structure: Hexagonal (Trigonal), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.65

Formation & geological history

Formed in hollow cavities in volcanic or sedimentary rocks. Over millions of years, mineral-rich groundwater seeps into these cavities, precipitating quartz crystals that grow inward from the outer shell.

Uses & applications

Predominantly used as decorative specimens, in jewelry (cut as cabochons), for spiritual/meditation practices, and as educational earth science tools for collectors.

Geological facts

Geodes appear as ordinary, round rocks on the outside, but their hollow interiors contain beautiful crystal formations. The term 'geode' comes from the Greek word 'Geoides' meaning 'earth-like'.

Field identification & locations

Identify in the field by looking for unusually light, hollow-feeling round nodules with a bumpy outer texture. Common locations include Brazil, Uruguay, Morocco, and the Midwestern United States (Iowa/Illinois).