Mineral

Quartz Geode

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale. Color: Clear to milky white crystals. Luster: Vitreous (glassy). Crystal structure: Hexagonal/Trigonal. Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

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

Identified March 31, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale. Color: Clear to milky white crystals. Luster: Vitreous (glassy). Crystal structure: Hexagonal/Trigonal. Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

Formation & geological history

Formed in hollow cavities (vugs) within igneous or sedimentary rocks. Over millions of years, mineral-rich groundwater seeps into the cavity, precipitating quartz crystals on the interior walls. Common in volcanic ash beds or limestone formations.

Uses & applications

Primary uses include ornamental decor, metaphysical/collecting markets, and as a source of high-purity silica for the electronics industry when found in bulk.

Geological facts

Geodes are often indistinguishable from common rocks on the outside. The name 'geode' comes from the Greek word 'Geoides' which means 'earth-like'. No two geode interiors are exactly identical.

Field identification & locations

Field identification: Look for round or egg-shaped stones that feel lighter than they look (indicating a hollow center). Often found in dry creek beds or areas with volcanic history like Brazil, Mexico, or the Midwest USA.