Polished Green Opal slab GRN86 oldest agate in the world Dimensions approximately 160 mm x

Dimensions approximately 160 mm x 130 mm x 90 mm thick

285 mm x 90 mm x 10 mm thick

natural back and a cut base to stand on

Dimensions at widest points approximately 140 mm x 90 mm x 65 mm thick

Polished Green Opal slab GRN86 oldest agate in the world Dimensions approximately 160 mm xGRN86 Green Opal & Magnesite slab, cut and polished on one side . Dimensions at widest points approximately 110 mm x 60 mm x 11 mm thick Weighs 107 grams Green Opal occurs at a location south of Kalgoorlie in the Eastern Goldfields of Western Australia. The green colouration is caused by traces of nickel and or chromium. Sometimes it exhibits striking contrasting veins of magnesite.