mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Clear to white crystals; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Clear to white crystals
Luster: Vitreous (glassy)

Identified June 13, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Clear to white crystals; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed in hollow cavities of volcanic or sedimentary rocks. Soluble minerals are deposited by hydrothermal fluids or groundwater over millions of years, growing crystals inward from the outer shell.

Uses & applications

Primarily used for decorative display pieces, jewelry (beads or pendants), crystal healing practices, and as educational specimens for geology students.

Geological facts

Geodes are often referred to as 'thunder eggs.' While they look like ordinary rocks on the outside, their hollow interiors can contain a variety of minerals including amethyst, citrine, and hematite.

Field identification & locations

Identify in the field by looking for rounded, lumpy stones that feel unexpectedly light for their size. Common locations include Brazil, Mexico, and the Midwestern United States (Iowa/Illinois).