mineral

Tumbled amber-colored agate or jasper

Microcrystalline quartz (SiO₂), likely chalcedony with iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; dark brown to black with translucent amber-brown areas, waxy-to-glassy luster, and no visible cleavage. It has a cryptocrystalline quartz structure and rounded, polished surfaces from tumbling.

Identified September 2, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich groundwater deposited chalcedony in cavities or fractures, with iron oxides producing the brown coloration; typically Paleozoic to Cenozoic in age depending on locality.

Uses & applications

Used as a decorative tumbled stone, cabochon, bead, or paperweight; attractive pieces may be collected, though this specimen appears commercially polished rather than gem grade.

Geological facts

The appearance may also overlap with common brown jasper or opaque agate; transmitted light showing internal banding would support agate identification.

Field identification & locations

Common in volcanic terrains and alluvial gravel deposits worldwide, especially Brazil, Uruguay, Mexico, India, Madagascar, and the western United States. Check translucency, curved fracture, and hardness; it should scratch glass but not quartz.