mineral

Agate (Moss or Banded Agate variety)

Agate (Silicon Dioxide - SiO2)

Hardness: 6.5–7 on Mohs scale. Color: Translucent with red, black, and grey inclusions. Luster: Vitreous to waxy. Crystal Structure: Trigonal/Cryptocrystalline. Cleavage: None, exhibits conchoidal fracture.

Hardness: 6
Color: Translucent with red, black, and grey inclusions
Luster: Vitreous to waxy

Identified May 21, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities (vesicles) of volcanic rocks (lava). Silica-rich fluids deposit layers or dendritic patterns over thousands of years. Often found in basalt flows or sedimentary gravel beds. Geological age varies significantly by deposit site.

Uses & applications

Used primarily for lapidary work, jewelry making (cabochons), and as ornamental stones. Also historically used for precision bearings and mortars/pestles due to its hardness.

Geological facts

Agate is a variety of chalcedony. The red coloration is often caused by iron oxides (hematite), while the black patterns are typically manganese oxides. It has been used for talismans and ornamentation for over 3,000 years, notably in ancient Greece.

Field identification & locations

Identify by its waxy luster and translucency when held to light. Often found in riverbeds, glacial till, or beaches as smooth pebbles. Check for banding or 'moss' like inclusions typical of microcrystalline quartz.

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Mineral/Rock

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