mineral

Tumbled brown chalcedony (likely jasper or agate)

Microcrystalline quartz, SiO₂; chalcedony with iron-oxide staining

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; opaque to slightly translucent, tan-brown with cream swirls, waxy to vitreous luster, and no visible cleavage. Its rounded form is mechanically tumbled and polished.

Identified August 8, 2026More mineral →

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Physical properties

Hardness 6.5–7 Mohs; opaque to slightly translucent, tan-brown with cream swirls, waxy to vitreous luster, and no visible cleavage. Its rounded form is mechanically tumbled and polished.

Formation & geological history

Silica-rich groundwater filled cavities or fractures in volcanic or sedimentary rock, later depositing cryptocrystalline quartz; brown coloration comes from iron oxides. The specimen’s precise geological age and locality cannot be determined from the image.

Uses & applications

Used for cabochons, beads, carvings, decorative stones, and lapidary collections; generally unsuitable as a major construction stone in this small form.

Geological facts

Chalcedony is quartz made of extremely fine intergrowths of quartz crystals and commonly forms colorful varieties such as jasper, agate, and carnelian.

Field identification & locations

Identify by its waxy surface, very high hardness, lack of cleavage, and resistance to scratching by steel; quartz crystals, glassy cleavage faces, or fizzing in acid would suggest alternatives. Common worldwide, especially in volcanic terrains.