mineral

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Hardness: 7 on the Mohs scale; Color: Milky white to translucent; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: Milky white to translucent
Luster: Vitreous (glassy)

Identified February 16, 2026More mineral →

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Physical properties

Hardness: 7 on the Mohs scale; Color: Milky white to translucent; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed via hydrothermal activity within cavities of volcanic or sedimentary rocks. Silica-rich groundwater penetrates hollow pockets (vesicles) and slowly precipitates quartz crystals over thousands of years. These can range from tens of thousands to millions of years old.

Uses & applications

Primarily used for decorative purposes, crystal healing/metaphysical collections, educational specimens, and small lapidary projects like cabochons.

Geological facts

Geodes are often called 'thunder eggs' when filled with agate. The word 'geode' comes from the Greek word 'Geoides' meaning 'earth-like'. Quartz is the most abundant mineral in Earth's continental crust.

Field identification & locations

Identify in the field by looking for rounded, bumpy, cauliflower-like rocks that feel lighter than they look (if they are hollow). Found globally, with famous deposits in Morocco, Mexico, and the Midwestern United States. Collectors should look for internal cavities with well-defined terminations.