gemstone

Tumbled moss agate (probable)

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

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent gray-beige to olive-brown with cloudy dendritic inclusions; vitreous to waxy luster, no visible cleavage, trigonal microcrystalline structure; rounded and polished by tumbling.

Identified August 23, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with mineral inclusions creating moss-like patterns; commonly Cenozoic to older volcanic-hosted deposits. The pictured piece is human-polished.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and inexpensive collector specimens; durable enough for jewelry but less valuable than vividly patterned agate.

Geological facts

“Moss agate” is a trade name rather than a distinct mineral species; its inclusions are commonly chlorite, hornblende, manganese oxides, or iron oxides—not actual moss.

Field identification & locations

Identify by waxy translucent chalcedony, rounded polish, and branching or cloudy inclusions; common sources include India, Brazil, Uruguay, the United States, and Australia. A destructive test is unnecessary—use a loupe and hardness comparison.