Rock Identifier
Agate (Cryptocrystalline quartz, Chalcedony (SiO2)) — mineral
mineral

Agate

Cryptocrystalline quartz, Chalcedony (SiO2)

AI-generated identification · may be incorrect

Mohs hardness 6.5-7. Waxy luster. Color variations include brown, orange, white banding. Cryptocrystalline structure. No cleavage.

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Physical properties

Mohs hardness 6.5-7. Waxy luster. Color variations include brown, orange, white banding. Cryptocrystalline structure. No cleavage.

Formation & geological history

Forms in voids of volcanic rocks or ancient lavas. Ground waters carrying silica seep into these voids, depositing layers of silica.

Uses & applications

Lapidary material, jewelry making, ornamental stone, rock collecting.

Geological facts

Agate was highly valued as a talisman or amulet in ancient times. It was believed to quench thirst and protect from fevers.

Field identification & locations

Identify by its waxy luster, conchoidal fracture, and often by banding or distinct patterns. Commonly found worldwide in volcanic areas or as alluvial deposits.