mineral

Blue Banded Agate (Dyed)

Silicon Dioxide (SiO2) - Variety of Chalcedony

Hardness: 6.5–7 on the Mohs scale; Color: Naturally grey, white, or brown but dyed vibrant blue in the specimen; Luster: Vitreous to waxy; Crystal structure: Hexagonal (cryptocrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.64.

Hardness: 6
Luster: Vitreous to waxy

Identified March 28, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities (vesicles) of volcanic rock or ancient lava flows where silica-rich groundwater deposits successive layers of microcrystalline quartz over thousands of years. Natural blue agate is rare; most vibrant blue specimens are porous agates that have been chemically dyed.

Uses & applications

Used primarily in jewelry as pendants or beads, ornamental carving, and in 'metaphysical' collections. Industrially, natural agate is used for precision pendulums, mortars and pestles, and laboratory equipment due to its hardness and resistance to acids.

Geological facts

Agate was named by Theophrastus, a Greek philosopher, who discovered the stone along the shore line of the river Achates in modern-day Sicily. Agate is often dyed because its porous structure allows it to absorb pigments uniformly, a practice that dates back to the Roman Empire.

Field identification & locations

Identify in the field by looking for translucent nodules with concentric banding and a waxy luster on broken surfaces. Common locations include Brazil (the source of most dyed agate), Uruguay, and the Lake Superior region of the USA. Dyed specimens can be identified by their 'unnatural' neon intensity and dye concentrations in tiny surface cracks.

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