I've just bought a strand (well several actually) of lemon yellow
Chrysoprase is a variety of Chalcedony, the microcrystalline form of
Quartz. High quality translucent material is the most valuable variety
of Chalcedony. However, Chrysoprase is not yellow, but the apple
green variety which is derived from the presence of nickel. It is
found in a number of localities including Australia, Austria, Russia,
Brazil and California. If you’re interested in gemstone lore,
Chrysoprase was used for spiritual protection.