mineral

Agate (Moss or Plume Agate variety)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale). Color: White, translucent centers with brown, orange, and green inclusions. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None, conchoidal fracture.

Hardness: 6
Luster: Vitreous to waxy

Identified May 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks, particularly volcanic lavas. Most are deposited in layers or dendritic patterns over thousands of years.

Uses & applications

Used primarily in lapidary arts, jewelry (cabochons), interior decoration, and as a collector's specimen. Historically used for making mortars and pestles because of its hardness.

Geological facts

Agates are found inside geodes or as nodules in volcanic rock. The unique colors are often caused by trace amounts of iron, manganese, or nickel. Many specimens from the American West date back to the Eocene epoch.

Field identification & locations

Identify in the field by its waxy texture and translucent 'window' when held to light. It lacks the graininess of sandstone and is hard enough to scratch glass. Commonly found in riverbeds or desert regions of the Western US.

Other mineral specimens

See all

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