gemstone

Dyed blue banded agate (tumbled)

Microcrystalline quartz, SiO₂ (chalcedony variety)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; waxy to vitreous luster; blue, white, gray, and dark curved bands, with no visible cleavage. Agate is cryptocrystalline quartz with specific gravity around 2.60–2.65; the vivid blue color is likely artificial dye.

Identified August 15, 2026More gemstone →

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Physical properties

Formation & geological history

Agate forms when silica-rich groundwater fills cavities in volcanic rocks, depositing chalcedony in successive bands. The host material may be Paleozoic to Cenozoic, depending on locality; tumbling and dyeing are human processing steps.

Uses & applications

Used for inexpensive jewelry, carvings, ornaments, cabochons, and decorative stones. This small tumbled piece is primarily a craft or collector item.

Geological facts

Concentric or curved banding reflects changing chemistry during repeated silica deposition. Agate can accept dye readily because microscopic pores and fractures allow color penetration.

Field identification & locations

Identify by its curved banding, translucent edges, hardness, and waxy surface; glass typically has bubbles and lacks natural band structure. Common sources include Brazil, Uruguay, India, Madagascar, and Mexico.