mineral

Quartz Geode

Silicon Dioxide (SiO2) within Sedimentary host rock

Hardness: 7 (Quartz); Color: White/clear crystals in tan/beige matrix; Luster: Vitreous (crystals) to dull (exterior); Crystal structure: Hexagonal/Trigonal; Cleavage: None/Conchoidal fracture.

Hardness: 7 (Quartz)
Color: White/clear crystals in tan/beige matrix
Luster: Vitreous (crystals) to dull (exterior)

Identified July 21, 2026More mineral →

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Physical properties

Hardness: 7 (Quartz); Color: White/clear crystals in tan/beige matrix; Luster: Vitreous (crystals) to dull (exterior); Crystal structure: Hexagonal/Trigonal; Cleavage: None/Conchoidal fracture.

Formation & geological history

Formed as secondary mineral precipitates in hollow cavities in sedimentary limestone or volcanic rock. Groundwater rich in dissolved silica permeates the cavity, slowly growing crystals inward over millions of years.

Uses & applications

Primarily used as decorative display pieces, educational specimens, and in metaphysical practices. Large, high-quality geodes are sought after by collectors.

Geological facts

Geode comes from the Greek word 'Geoides' meaning 'earth-like'. They appear as ordinary rocks on the exterior, hiding beautiful crystal interiors that are only revealed when cracked open or cut.

Field identification & locations

Look for rounded or lumpy rocks that feel lighter than they look (indicating a hollow center). Common in desert environments such as Morocco, Mexico (Chihuahua), and the US (Iowa, Utah, Arizona).

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