mineral

Green tumbled agate (likely green chalcedony)

Chalcedony, microcrystalline quartz (SiO₂); exact identification is uncertain from the photo

AI-generated identification · may be incorrect

Smooth, opaque-to-translucent dark-green pebble with a waxy to vitreous luster. Quartz hardness is about 6.5–7 Mohs; crystals are microscopic and no cleavage is visible.

Identified September 25, 2026More mineral →

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Physical properties

Smooth, opaque-to-translucent dark-green pebble with a waxy to vitreous luster. Quartz hardness is about 6.5–7 Mohs; crystals are microscopic and no cleavage is visible.

Formation & geological history

Forms when silica-rich fluids deposit quartz in cavities or fractures, commonly in volcanic rocks; the specimen has been tumbled and may be dyed. Geological age cannot be determined from appearance.

Uses & applications

Used for inexpensive jewelry, beads, cabochons, and decorative pieces; agate is also collected and used for ornaments.

Geological facts

Agate is a banded variety of chalcedony, though bands are not apparent on this small polished piece.

Field identification & locations

Look for fine banding, translucency at thin edges, and hardness sufficient to scratch glass; vivid, uniform green color may indicate treatment. Chalcedony occurs worldwide, including Brazil, India, Uruguay, and the United States.