sedimentary

Druzy Quartz on Matrix (Chert/Limestone)

Silicon Dioxide (SiO2) with Carbonate host rock

Hardness: 7 (quartz) to 3-4 (host rock). Color: White to yellowish crystals, brown/tan matrix. Luster: Vitreous (crystals) to dull (matrix). Crystal structure: Hexagonal. Cleavage: None (conchoidal fracture).

Hardness: 7 (quartz) to 3-4 (host rock)
Color: White to yellowish crystals, brown/tan matrix
Luster: Vitreous (crystals) to dull (matrix)

Identified July 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the precipitation of silica from groundwater within cavities and fractures of sedimentary rock, typically during diagenesis or hydrothermal activity. Often found in karst environments.

Uses & applications

Aesthetic display specimens for collectors, decorative landscaping, and occasionally lapidary use for jewelry if the druzy layer is stable.

Geological facts

The word 'druzy' refers to a coating of fine crystals on a rock surface. This specimen appears to have some algal or moss growth on the exterior, suggesting it was found near the surface or in a damp environment.

Field identification & locations

Identify in the field by looking for vugs (pockets) in limestone or chert outcrops. Collectors look for the sparkle of small quartz faces inside cavities. Found worldwide, extremely common in the Midwestern United States.

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