sedimentary

Blue Agate (Dyed Chalcedony)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: Vivid blue (unnatural saturation), Luster: Vitreous to waxy, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None, Specific Gravity: 2.60-2.65

Hardness: 6

Identified June 30, 2026More sedimentary →

Explore Blue Agate (Dyed Chalcedony) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Vivid blue (unnatural saturation), Luster: Vitreous to waxy, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None, Specific Gravity: 2.60-2.65

Formation & geological history

Formed as a microcrystalline variety of silica, typically occurring within volcanic rock cavities or sedimentary geodes. Natural blue agate is rare and pale; this specific intense blue is achieved through dyeing translucent chalcedony.

Uses & applications

Commonly used for decorative ornaments, tumbled stones for collectors, 'worry stones', inexpensive costume jewelry, and lapidary practice.

Geological facts

Agate has been used for over 3,000 years, originally named after the Achates River in Sicily. Most bright blue agate found in gift shops is actually Brazilian chalcedony that has been soaked in a chemical solution to achieve the electric blue hue.

Field identification & locations

Identify in the field by its conchoidal fracture and hardness (won't be scratched by a steel blade). To identify if it is dyed, look for color concentration in small cracks or bands that look too vibrant to be natural. Commonly found in Brazil, Uruguay, and India.