mineral

Tumbled chalcedony (likely moss or dendritic agate)

Microcrystalline quartz, SiO₂, with iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent gray-white body with yellow-orange and dark gray-brown inclusions, waxy to vitreous luster, and no visible cleavage. The rounded edges indicate tumbling or natural water abrasion.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich groundwater deposited microcrystalline quartz in cavities or fractures, while iron oxides and other minerals produced the mottling. These varieties commonly formed in volcanic rocks during the Cenozoic, though exact age depends on locality.

Uses & applications

Used for cabochons, beads, carvings, lapidary pieces, and ornamental objects; attractive specimens have modest jewelry and collecting value.

Geological facts

The orange coloration is typically limonite/goethite staining rather than quartz itself. Chalcedony is a quartz variety composed of extremely fine intergrowths of quartz crystals.

Field identification & locations

Identify it by its waxy translucence, conchoidal fracture, lack of cleavage, and resistance to scratching by a steel knife; it should scratch ordinary glass. Common sources include Brazil, Uruguay, India, Madagascar, and the western United States.