mineral

Agate (Plume or Moss Agate variant)

Chalcedony (SiO2) with various inclusions

Hardness: 6.5-7 (Mohs scale), Color: Variegated with earthy browns, greys, and translucent purples, Luster: Waxy to vitreous, Crystal structure: Trigonal (microcrystalline/cryptocrystalline), Cleavage: None (conchoidal fracture)

Hardness: 6

Identified June 6, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily within volcanic and metamorphic rocks through the deposition of silica from groundwater into cavities or fissures, often occurring in secondary geological deposits across various ages from the Precambrian to Cenozoic.

Uses & applications

Widely used for ornamental jewelry (cabochons), lapidary art, collection specimens, and historically for precision mechanical parts due to its hardness.

Geological facts

Agate is named after the Achates River in Sicily where it was first discovered. This specimen shows a mix of microcrystalline quartz and likely iron or manganese oxide inclusions that create the mossy or dendritic patterns visible.

Field identification & locations

Identified by its waxy luster, translucency, and inability to be scratched by a steel knife. Common in the western United States, Brazil, and India. Collectors look for unique internal patterns and color bands.

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

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Epidote

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

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Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

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

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic