Commercial quantities of gem-quality chrysoprase and green prase opal (nickel-bearing chalcedony and common opal, respectively) have been recovered from altered serpentinite deposits near Haneti, ...

and lemon chrysoprase from Australia. Top row: glacier stone from Idaho, bertrandite from Utah, and black jasper from Oregon. Courtesy of Columbia Gem House. Photo by Eric Welch. At the AGTA show, ...