gemstone

Tumbled moss agate (likely)

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

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent gray-white body with brown, rusty, and possibly green dendritic inclusions; vitreous to waxy luster, no visible cleavage, cryptocrystalline structure. The rounded, polished form indicates tumbling.

Identified August 19, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing chalcedony and trapping iron- or manganese-oxide inclusions. Most specimens are Cenozoic to older volcanic-hosted material; exact age and locality cannot be determined from the image.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and inexpensive collector specimens; durable enough for jewelry, though porous fractures may reduce toughness.

Geological facts

Despite its name, moss agate is not a true agate unless it has recognizable banding; similar material may be called scenic agate or included chalcedony. Its patterns are mineral inclusions, not organic moss.

Field identification & locations

Identify by translucency, waxy polish, hardness, and branchlike inclusions; it should scratch glass but not quartz. Common sources include India, Brazil, Uruguay, the United States, and Madagascar.