Green Chalcedony

Physical Properties

Hardness: 6.5-7 on the Mohs scale; Color: Pale to deep green; Luster: Waxy to vitreous; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64.

Formation & Geological History

Formed from the precipitation of silica-rich water in volcanic cavities (vugs) or sedimentary environments at relatively low temperatures over millions of years.

Uses & Applications

Primarily used in jewelry (beads, cabochons), ornamental carvings, seals, and as a collector's specimen. Historically used for amulets and tools.

Geological Facts

Green chalcedony is often called 'Chrysoprase' when colored by nickel or 'Prase' when colored by chlorite. It has been used since ancient Greek and Roman times as a decorative gemstone.

Field Identification & Locations

Identify by its waxy luster, lack of visible grain, and green translucency. Common locations include Brazil, India, Madagascar, and the USA (California/Oregon). Collectors should look for even color distribution and translucency.

Identified on: 4/13/2026

Mode: Standard