mineral

Quartz Geode

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Clear to white internal crystals with tan/grey outer shell; Luster: Vitreous (glassy) inside, dull/earthy outside; Crystal Structure: Hexagonal (trigonal); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Clear to white internal crystals with tan/grey outer shell
Luster: Vitreous (glassy) inside, dull/earthy outside

Identified June 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities within sedimentary or volcanic rocks. Mineral-rich groundwater seeps into hollow vesicles or bubbles, precipitating crystals over thousands to millions of years.

Uses & applications

Primarily used for decorative purposes, crystal healing, educational specimens, and as a popular item for lapidary hobbies and rock collecting.

Geological facts

The word 'geode' comes from the Greek word 'Geoides' meaning 'earth-like'. No two geodes are exactly alike, and the largest geodes can be big enough for humans to stand inside.

Field identification & locations

Identify in the field by looking for rounded, bumpy, potato-like rocks that feel lighter than they look (indicating a hollow center). Common in desert regions of the SW United States, Brazil, and Mexico.