gemstone

Polished moss agate (probable)

Chalcedony, microcrystalline quartz (SiO₂), with iron/manganese inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent gray-brown body with green-brown, mossy inclusions and vitreous-to-waxy luster. Trigonal quartz structure, no cleavage, conchoidal fracture; polished cabochon form.

Identified August 16, 2026More gemstone →

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Physical properties

Hardness 6.5–7 Mohs; translucent gray-brown body with green-brown, mossy inclusions and vitreous-to-waxy luster. Trigonal quartz structure, no cleavage, conchoidal fracture; polished cabochon form.

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, with dendritic iron or manganese minerals creating moss-like patterns. Most specimens are Cenozoic to older, depending on the host lava.

Uses & applications

Used for cabochons, beads, pendants, and decorative objects; generally an affordable jewelry stone.

Geological facts

Despite its name, moss agate usually contains mineral dendrites rather than biological moss. The pictured stone could also be another patterned chalcedony, such as plume agate, without testing.

Field identification & locations

Identify by its waxy luster, translucency, lack of cleavage, and branching internal inclusions; common sources include India, Brazil, Uruguay, the United States, and Australia. Refractive index or microscopic examination helps confirm it.