Nickeloan magnesite (Lemon Chrysoprase)

This attractive rock is found in the Eastern Goldfields area of Western Australia in a belt of ultramafic rocks that stretch from  Norseman in the south to near Wiluna in the north.   It occurs in many of the same locations as that of chrysoprase, most notably Yerilla , Marshall Pool & Goongarrie but in numerous other places as well.

Magnesite is magnesium carbonate and occurs as veins & nodules  and is an alteration product of serpentine and other magnesium rich rock types. This is produced by hydrothermal leaching of the magnesium from the serpentine. 

In Western Australia most magnesite is white, however in certain locations the presence of nickel mineralisation is responsible for the pleasing green colour found in "lemon chrysoprase".