mineral

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Clear to white. Luster: Vitreous (glassy). Crystal Structure: Hexagonal/Trigonal (druzy). Specific Gravity: 2.65.

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

Identified April 29, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale. Color: Clear to white. Luster: Vitreous (glassy). Crystal Structure: Hexagonal/Trigonal (druzy). Specific Gravity: 2.65.

Formation & geological history

Formed as mineral-rich water precipitates inside cavities of volcanic or sedimentary rocks. Over thousands of years, crystals grow inward from the outer shell.

Uses & applications

Commonly used for home decor, educational specimens, metaphysical collecting, and occasionally as a source of high-purity silica for electronics.

Geological facts

Geodes are often called 'thunder eggs' when they are completely filled with minerals. This specific piece shows a druzy quartz coating on a chalcedony or host-rock base.

Field identification & locations

Identify in the field by looking for rounded, hollow-sounding nodules that look like ordinary stones on the outside. Common in Brazil, Mexico, and the USA (Iowa, Oregon).