mineral

Druzy Agate (specifically Black Druzy Agate)

Silicon Dioxide (SiO2)

Hardness: 6.5 - 7 on the Mohs scale. Color: Deep black to charcoal grey. Luster: Vitreous (glassy) for the agate, sparkling/adamantine for the tiny crystals. Crystal structure: Trigonal (microcrystalline/cryptocrystalline). Specific Gravity: 2.60 - 2.65.

Hardness: 6
Color: Deep black to charcoal grey

Identified March 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the slow deposition of silica from groundwater within cavities (vugs) of igneous volcanic rocks. The 'druzy' sparkling effect occurs when tiny quartz crystals form over a pre-existing mineral or rock surface during the final stages of cooling.

Uses & applications

Primary use is in jewelry (cabochons, pendants, cocktail rings) and as a decorative collector's specimen. Its glittery surface makes it highly desirable for 'boho' and statement fashion jewelry.

Geological facts

The word 'druzy' (or drusy) refers to the minute sparkling crystals that look like sugar dusting. While agate is technically a variety of chalcedony, black druzy is often treated or dyed to enhance the darkness of the background and the sparkle of the crystals.

Field identification & locations

Identify in the field by looking for vugs (hollow cavities) in volcanic rock. To identify this specific specimen: check for the characteristic sparkling surface texture paired with the smooth, translucent-to-opaque outer chalcedony band. Commonly found in Brazil, India, and the United States (Oregon/Arizona).

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