mineral

Botryoidal chalcedony geode

Microcrystalline quartz (SiO₂), commonly with drusy quartz and iron-oxide staining

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; white, cream, honey, and pale pink-brown colors; waxy to vitreous luster with sparkling drusy crystals. It has a cryptocrystalline quartz structure, no cleavage, conchoidal fracture, and specific gravity about 2.6.

Identified August 28, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich groundwater filled cavities in volcanic rock or sediment, depositing chalcedony in rounded botryoidal layers followed by quartz crystals; formation is generally Cenozoic to older, depending on locality.

Uses & applications

Used as a decorative specimen, lapidary material, cabochons, carvings, and occasionally jewelry; attractive geodes and large botryoidal pieces may be collectible.

Geological facts

The specimen appears to be a broken or cut cavity lined with drusy quartz, with brown coloration likely caused by iron oxides. Chalcedony is quartz whose crystals are too small to see individually.

Field identification & locations

Identify it by its rounded lumpy chalcedony texture, quartz sparkle, glass-scratching hardness, and lack of cleavage; common sources include Brazil, Uruguay, Mexico, Morocco, and the western United States.