mineral

Tumbled brown agate or jasper

Microcrystalline quartz, SiO₂ (likely chalcedony/agate with iron oxides)

AI-generated identification · may be incorrect

Small rounded, polished pebble with dark brown, gray, and rusty-orange coloration and a waxy-to-subvitreous luster. Quartz hardness is about 6.5–7 Mohs; no visible cleavage, cryptocrystalline structure, and specific gravity near 2.6.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or fractures in volcanic rock, with iron impurities producing brown-red colors; individual material may range from Paleozoic to Cenozoic in age. Exact identification is limited because the specimen is small and out of focus.

Uses & applications

Used for tumbled stones, cabochons, ornamental objects, and low-cost jewelry; larger patterned pieces can be collectible.

Geological facts

Agate is banded chalcedony, whereas jasper is opaque, impurity-rich chalcedony; this specimen’s apparent lack of visible banding makes jasper or brown chalcedony plausible.

Field identification & locations

Commonly found in volcanic terrains and gravel deposits worldwide, especially Brazil, Uruguay, India, Madagascar, and the western United States. A glassy/waxy surface, high hardness, and inability to scratch it with steel support chalcedony; acid produces no reaction.