mineral
Tumbled green agate (likely moss or chalcedony agate)
Cryptocrystalline quartz, SiO₂; likely green chalcedony with possible chlorite or iron inclusions
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; translucent pale green to gray-green, waxy/vitreous luster, no visible cleavage, and a smoothly tumbled surface. Specific gravity is about 2.6; the rounded shape and uniform polish indicate human processing.
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Physical properties
Hardness 6.5–7 Mohs; translucent pale green to gray-green, waxy/vitreous luster, no visible cleavage, and a smoothly tumbled surface. Specific gravity is about 2.6; the rounded shape and uniform polish indicate human processing.
Formation & geological history
Agate forms when silica-rich groundwater fills cavities in volcanic rocks, commonly during the Cenozoic or older volcanic episodes; green coloration may come from chlorite, celadonite, or other inclusions. Exact identification and age require testing or locality information.
Uses & applications
Used for inexpensive jewelry, cabochons, beads, carvings, and decorative objects. Common tumbled pieces typically have modest collector value.
Geological facts
Agate is a variety of chalcedony, itself microcrystalline quartz. A waxy appearance, translucency, and resistance to scratching distinguish it from many similarly colored glass or plastic imitations.
Field identification & locations
Commonly found in volcanic terrains worldwide, including Brazil, Uruguay, India, Madagascar, Mexico, and the United States. Confirm with a quartz-level hardness test and magnification; dyeing or surface coatings are possible.
