gemstone

Tumbled brown agate or jasper

Microcrystalline quartz (chalcedony), SiO₂; exact variety uncertain from the image

AI-generated identification · may be incorrect

Smooth, rounded, polished pebble with brown, reddish, and translucent gray zones; vitreous to waxy luster. Mohs hardness 6.5–7, no visible cleavage, cryptocrystalline structure, and specific gravity about 2.6.

Identified September 7, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or fractures in volcanic rock, later developing chalcedony, agate banding, or jasper; commonly Paleozoic to Cenozoic in age depending on locality.

Uses & applications

Used for tumbled stones, cabochons, beads, carvings, and inexpensive jewelry; also collected as a decorative specimen.

Geological facts

The translucent areas suggest chalcedony or agate, while opaque reddish-brown portions may be iron-stained jasper. A polished surface can obscure natural banding and textures.

Field identification & locations

Common in volcanic terrains and gravel deposits worldwide, especially Brazil, Uruguay, Mexico, India, Madagascar, and the western United States. Identification is supported by hardness, waxy appearance, translucency, and resistance to scratching by steel.