mineral

Agate

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on the Mohs scale. Color: Translucent to opaque with banding. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (trigonal). Cleavage: None. Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Translucent to opaque with banding
Luster: Vitreous to waxy

Identified March 9, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on the Mohs scale. Color: Translucent to opaque with banding. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (trigonal). Cleavage: None. Specific Gravity: 2.58–2.64.

Formation & geological history

Formed primarily within volcanic and metamorphic rocks. It occurs when silica-rich groundwater fills cavities left by gas bubbles in cooling lava. Most deposits range from the Precambrian to Cenozoic eras.

Uses & applications

Used extensively in jewelry (cabochons, beads), decorative carvings, precision scales, and industrial mortar and pestles due to its hardness and chemical resistance.

Geological facts

Ancient Greeks and Romans used agates as amulets and signet rings. The famous 'Theophrastus' agate is among the first recorded descriptions. Many specimens are dyed to enhance their natural banding.

Field identification & locations

Identify in the field by its waxy texture and characteristic concentric or moss-like banding patterns. Common locations include Brazil, Uruguay, Germany, and the United States (Lake Superior region).