mineral

Banded Agate

Silicon Dioxide (SiO2) - Chalcedony variety

Hardness: 6.5-7 (Mohs scale). Color: White, gray, and blue-gray bands. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline (Trigonal). Cleavage: None (Conchoidal fracture). Specific Gravity: 2.60-2.65.

Hardness: 6
Color: White, gray, and blue-gray bands
Luster: Waxy to vitreous

Identified June 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in volcanic and metamorphic environments. Silica-rich groundwater fills cavities (vugs) in host rock, depositing layers of microcrystalline quartz over time. Most specimens occur in ancient basaltic lava flows.

Uses & applications

Used widely in lapidary arts for jewelry, beads, and polished palm stones. Also used in industry for mortar and pestles due to its hardness, and for precision pendulums and balances.

Geological facts

Agate was named by Theophrastus, a Greek philosopher, who discovered the stone along the shore of the Achates River in Sicily. No two agates are exactly alike due to the unique layering process during formation.

Field identification & locations

Identify in the field by its waxy appearance, translucency at edges, and characteristic concentric or parallel banding. Commonly found in riverbeds, lakeshores (like Lake Superior), and volcanic regions. Collectors look for unbroken bands and high translucency.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral