Lemon Chrysoprase

It forms where serpentine and other ultramafic rocks are weathered or hydrothermally altered, as fracture fillings in peridotite, dunite and serpentinite and as nodules in the soil above them, the same settings as chrysoprase. Most comes from the Eastern Goldfields of Western Australia, in a belt of ultramafic rocks from Norseman to Wiluna, at localities such as Yerilla, Marshall Pool and Goongarrie. It often occurs in the same fractures and nodules as chrysoprase; nodules can have a chrysoprase core with magnesite around it or the reverse.

GIA's Gems & Gemology described material sold as "lemon chrysoprase" as a quartz–magnesite rock (Johnson and Koivula, 1996); other gemologists found magnesite and quartz together with some chrysoprase (Henn and Milisenda, 1997). Compared with true chrysoprase (hardness about 6–7, SG about 2.60, translucent), it is opaque to semitranslucent, softer (about 4) and heavier (about 3.0), and its magnesite effervesces in warm hydrochloric acid, a destructive test that should be left to a laboratory. Material that mixes green chrysoprase with yellow magnesite occurs too, informally called "lemon 'n' lime" at Marshall Pool.