mineral

Purple Dyed Agate Geode (Banded Chalcedony)

Silicon Dioxide (SiO2) - variety: Agate

Hardness: 6.5-7 (Mohs); Color: Naturally gray/white with artificial vivid purple dye; Luster: Vitreous to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Naturally gray/white with artificial vivid purple dye
Luster: Vitreous to waxy

Identified March 20, 2026More mineral →

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Physical properties

Formation & geological history

Formed as secondary deposits in volcanic rock cavities (gas bubbles) where silica-rich groundwater deposited layers of chalcedony over time. These geodes are typically millions of years old (Cretaceous to Miocene).

Uses & applications

Commonly used for ornamental bookends, home decor, metaphysical 'healing' crystals, and lapidary jewelry like cabochons.

Geological facts

While the banding and quartz interior are natural, the intense purple color is artificial; agate is very porous and easily absorbs dye. The hollow center containing tiny crystals is known as a druzy cavity.

Field identification & locations

Identify in the field by looking for nodular, potato-like stones with a warty exterior in volcanic basalt beds. Natural agates never occur in this neon/electric purple shade; if the color looks too bright to be real, it is dyed.

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