Polished Green Opal slab GRN86 oldest agate in the world Dimensions at widest points approximately

Dimensions at widest points approximately 80 mm x 60 mm x 32 mm thick

Weighs 224 grams

Weighs 163 grams

285 mm x 90 mm x 10 mm thick

Dimensions approximately 160 mm x 130 mm x 90 mm thick

Polished Green Opal slab GRN86 oldest agate in the world Dimensions at widest points approximatelyGRN86 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.