mineral

Banded Agate

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Brown, gray, and translucent blue-white; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Conchoidal fracture.

Hardness: 6
Color: Brown, gray, and translucent blue-white
Luster: Waxy to vitreous

Identified May 19, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Brown, gray, and translucent blue-white; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Conchoidal fracture.

Formation & geological history

Formed in cavities within volcanic or metamorphic rocks when silica-rich groundwater deposits layers of chalcedony over thousands of years. Usually found in ancient lava flows.

Uses & applications

Used extensively in jewelry (cabochons), lapidary arts, ornamental carvings, and historically for precision mechanical parts like mortar and pestles.

Geological facts

The banding in agate is caused by the rhythmic precipitation of silica. No two agates are exactly alike, making each specimen unique to its formation site.

Field identification & locations

Identified by its distinctive banding and translucency. Commonly found in riverbeds and beaches where volcanic activity occurred. Look for a waxy texture and banded interior when broken or polished.