mineral

Agate (Beads)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Multi-colored bands (purple, blue, green as shown are often dyed); Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline microquartz; Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Luster: Waxy to vitreous

Identified May 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed as nodules in volcanic rocks or ancient lavas, where silica-rich groundwater fills cavities and precipitates in layers. These are secondary minerals formed over millions of years.

Uses & applications

Primarily used in jewelry, ornamental carvings, and historical talismans. Industrially used for precision pendulums, mortars and pestles, and laboratory equipment due to chemical resistance.

Geological facts

Agate was first discovered along the Achates River in Sicily by the Greek philosopher Theophrastus. It has been used in jewelry for over 3,000 years, dating back to ancient Egypt and Babylon.

Field identification & locations

Identify in the field by its banded appearance and waxy luster when broken. Use a steel file (which won't scratch it) to distinguish it from glass. Found worldwide, notably in Brazil, Uruguay, and various US states.