mineral

Quartz geode (likely milky-quartz geode)

Crystalline silicon dioxide, SiO₂; quartz lining a geode cavity

AI-generated identification · may be incorrect

White to cream, opaque-to-translucent quartz with a vitreous luster; quartz hardness 7 Mohs, trigonal crystal system, no cleavage, conchoidal fracture, specific gravity about 2.65. The specimen appears cut open and weathered or iron-stained; crystal faces are not clearly visible.

Identified October 9, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited quartz inside a gas bubble or cavity in volcanic rock, or a void in sedimentary rock; the exact host and age cannot be determined from the photo. Geodes form over geological time and occur in rocks of many ages.

Uses & applications

Commonly split, polished, or displayed as a decorative and educational specimen; quartz also has extensive industrial uses in glassmaking and electronics.

Geological facts

Quartz is among Earth’s most abundant minerals and has a hardness of 7 on the Mohs scale.

Field identification & locations

Identify by the hard, glassy white material and cavity-filling texture; a scratch test and close view of crystal faces would help distinguish quartz from calcite. Geodes are found worldwide, including Brazil, Uruguay, and the US Midwest.