mineral

Yellow chalcedony (possibly jasper/chalcedony)

Microcrystalline quartz, SiO₂; yellow coloration likely from iron oxides/hydroxides

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque to slightly translucent, cream-yellow to ochre, with a waxy to glassy luster and conchoidal fracture. No visible cleavage; rounded and polished/tumbled.

Identified September 5, 2026More mineral →

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Physical properties

Hardness about 6.5–7 Mohs; opaque to slightly translucent, cream-yellow to ochre, with a waxy to glassy luster and conchoidal fracture. No visible cleavage; rounded and polished/tumbled.

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, later acquiring yellow coloration from iron staining; commonly Cenozoic to older, with age depending on locality.

Uses & applications

Used for cabochons, beads, carvings, and decorative objects; attractive polished pieces have modest lapidary value.

Geological facts

The specimen may be marketed as yellow jasper, but jasper is opaque chalcedony containing abundant impurities, while cleaner translucent areas are better called chalcedony.

Field identification & locations

Identify by testing scratch resistance against steel or glass, observing waxy luster, and checking for conchoidal fracture; common sources include Brazil, Madagascar, India, Indonesia, and the western United States.