mineral

Druzy Quartz on Host Rock

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Transparent to white crystals on a brown/tan host rock; Luster: Vitreous (glassy) for the crystals, dull for the matrix; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture).

Hardness: 7 (Mohs scale)
Color: Transparent to white crystals on a brown/tan host rock
Luster: Vitreous (glassy) for the crystals, dull for the matrix

Identified March 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed through hydrothermal precipitation where silica-rich fluids seep into cavities (vugs) within rock. As the fluid cools or pressure drops, small quartz crystals grow on the surfaces. Geological age varies by the age of the host rock, often millions of years old.

Uses & applications

Primary use is for lapidary work, jewelry (pendants/rings), and as decorative cabinet specimens for collectors.

Geological facts

The term 'druzy' (or drusy) refers to a coating of fine crystals on a rock surface that resemble granulated sugar. While common, clear and well-formed druzy is highly prized for its 'sparkle' effect under light.

Field identification & locations

Identify in the field by looking for sparkling, sugary textures inside rock cavities or vugs. Its hardness (cannot be scratched by a steel knife) distinguishes it from softer minerals like calcite. Found globally in volcanic and sedimentary environments.