Opal stone is one of the favourites of sculptors as it polishes to a high finish.Its famous for its smooth light milky green texture, with an almost translucent surface with sometimes an orangey iron deposit. The most prized opal comes from Chiweshe, two hours North of Harare. As with most stone it’s mined for the purpose of sculpting. Opal stone has the hardness of 5.0-6.0 on the Mohs hardness scale.