mineral

Yellow chalcedony (likely tumbled quartz)

Chalcedony, cryptocrystalline SiO₂; possibly iron-stained quartz or yellow jasper

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; honey-yellow to orange, waxy-to-glassy luster, translucent edges, and no visible cleavage. It consists of intergrown microscopic quartz crystals and has specific gravity around 2.6.

Identified September 14, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, often in volcanic rocks; yellow color commonly results from iron oxides or inclusions. Most specimens formed during relatively recent volcanic and hydrothermal episodes, with age varying by locality.

Uses & applications

Used for cabochons, beads, carvings, tumbled stones, and ornamental objects; durable material but generally modest gem value unless vividly colored or attractively patterned.

Geological facts

Chalcedony is a quartz variety encompassing microcrystalline and fibrous forms such as agate, onyx, and chrysoprase. Its color can be enhanced by dyeing or heat treatment.

Field identification & locations

Identify by its waxy appearance, smooth conchoidal fracture, lack of cleavage, and ability to scratch ordinary glass; it should not fizz in dilute acid. Common sources include Brazil, Uruguay, India, Madagascar, and the western United States.