mineral

Agate (Dyed High-Grade Polished Slice)

Silicon dioxide (SiO2), Chalcedony crystal variety

Hardness: 6.5–7 on Mohs scale; Color: Naturally translucent gray/white but artificially dyed teal and green in this specimen; Luster: Waxy to vitreous; Crystal structure: Hexagonal/Trigonal (Cryptocrystalline); Cleavage: None/Conchoidal fracture; Specific gravity: 2.58–2.64.

Hardness: 6
Luster: Waxy to vitreous

Identified March 31, 2026More mineral →

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Physical properties

Formation & geological history

Formed in the cavities of volcanic rocks or ancient lavas (vesicles). Ground-water rich in silica percolates through these cavities, depositing layers of microcrystalline quartz over thousands of years. Many commercial slices like this originate from volcanic deposits in Brazil and Uruguay.

Uses & applications

Used primarily for ornamental purposes, jewelry (pendants, cabochons), bookends, coasters, and as healing crystals in many metaphysical practices. Industrial use includes high-precision mortars and pestles due to its hardness.

Geological facts

Agate is named after the Achates River in Sicily, where it was first discovered in ancient times. The concentric banding visible in this specimen is caused by the rhythmic crystallization of silica. This particular green/teal color is rarely found in nature and is most often achieved through chemical dyeing processes.

Field identification & locations

Identify by its translucent nature and distinct concentric or 'fortification' banding patterns. In the field, look for rounded nodules with a rough, 'cauliflower-like' exterior in basaltic or sedimentary regions. Often found in riverbeds where erosion has released them from host rocks.

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