gemstone

Polished moss agate (likely)

Chalcedony, microcrystalline SiO₂, with included green minerals such as chlorite or hornblende

AI-generated identification · may be incorrect

Translucent, waxy-to-glassy luster with rounded tumbled surfaces; green, brown, amber, and gray internal plume-like inclusions. Mohs hardness 6.5–7; no cleavage; trigonal cryptocrystalline quartz; specific gravity about 2.58–2.65.

Identified September 8, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rock, with later mineral inclusions producing moss-like patterns. Most specimens are Cenozoic to Mesozoic in host-rock age, depending on locality.

Uses & applications

Used for cabochons, beads, carvings, and ornamental objects; attractive pieces have modest jewelry and collector value.

Geological facts

Despite its plant-like appearance, the green pattern is mineral inclusion rather than fossilized moss. Color zoning and translucency are especially diagnostic.

Field identification & locations

Common sources include India, Brazil, Uruguay, the United States, and Madagascar. Identify it by testing hardness against ordinary glass, observing curved conchoidal fracture, and checking that inclusions are enclosed within translucent chalcedony; avoid acid testing.