mineral

Banded Agate

Chalcedony (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Multi-colored bands (white, grey, brown); Luster: Waxy to vitreous; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64

Hardness: 6
Color: Multi-colored bands (white, grey, brown)
Luster: Waxy to vitreous

Identified June 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities of volcanic rocks or ancient lavas (geodes) through the deposition of silica from groundwater in concentric layers over millions of years. This specimen likely dates back to the Cenozoic or Mesozoic era depending on the source basalt.

Uses & applications

Widely used for lapidary arts, jewelry (cabochons), interior decoration (coasters/bookends), and historically for precision tools like mortar and pestles due to its hardness.

Geological facts

Agate is named after the Achates River in Sicily where it was first discovered. The concentric banding is technically known as 'rhythmically deposited' microcrystalline quartz.

Field identification & locations

Identify by looking for translucent to opaque concentric bands and a waxy surface. Often found in riverbeds or gravel pits in volcanic regions like the Lake Superior area, Brazil, or Oregon. To identify, check for its ability to scratch glass and the presence of distinct curved banding.