Chrysoprase is a variant of Chalcedony, or cryptocrystalline quartz, which means it is made up of microscopically fine crystals. Trace amounts of nickel cause its signature green color, and in the rough it typically appears in colorful veins sandwiched by iron and magnesite-rich host rock.

Rough Tanzanian Chrysoprase from the Tucson Gem and Mineral Show

Chrysoprase has been used for adornment as far back as 400 BC, and is currently found in deposits all over the world. The most famous material is from the Marlborough mine in Australia, but I’m partial to the bluer, creamier variants found in Brazil, as well as the deep gemmy blue-green material found in Tanzania.

In Christian lapidaries of the Medieval era, chrysoprasus symbolized those who endured hardship but remained generous and open-hearted. Lapidaries often prescribed stones for medical and metaphysical ailments, and Chrysoprase was said to brighten the eyes and heal sprains. Beyond the physical benefits, Chrysoprase symbolized personal triumphs of all kinds: its wearer would overcome enemies, attract wealth, and be protected from myriad “misdeeds of the devil”.