sedimentary

Druzy Quartz Geode (Partially Open)

Silicon Dioxide (SiO2) within Sedimentary Host Rock

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Clear to white crystals in a grayish/brown matrix; Luster: Vitreous (glassy) crystals with earthy matrix; Crystal Structure: Hexagonal (trigonal); Cleavage: None; Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Clear to white crystals in a grayish/brown matrix
Luster: Vitreous (glassy) crystals with earthy matrix

Identified July 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when mineral-rich groundwater percolates through cavities in sedimentary or volcanic rock. Over thousands of years, silica precipitates out of the water to form layers of chalcedony and eventually crystalline quartz. These particular specimens are common in limestone or shale beds from the Paleozoic or Mesozoic eras.

Uses & applications

Commonly used for home decor, educational material in geology, and minor jewelry (when cut into druzy cabs). Lapidary artists use them for polishing or as display pieces.

Geological facts

Geodes are virtually indistinguishable from ordinary rocks on the outside until cracked open. The word 'geode' comes from the Greek word 'Geoides,' meaning 'earth-like.' These specimens often represent a micro-environment that has remained sealed for millions of years.

Field identification & locations

Identify in the field by looking for rounded, bumpy, or hollow-sounding nodules that feel lighter than solid rocks of the same size. Common locations include the Midwest USA (Keokuk geodes), Brazil, and Morocco. Collectors should look for well-defined crystal terminations and lack of damage.