Polished Green Opal slab GRN99. oldest agate in the world Dimensions at widest points approximately

Dimensions at widest points approximately 100 mm x 90 mm

Weight 435 grams

Dimensions at widest points approximately 60 mm x 45 mm x 25 mm thick

Weighs 93 grams

Weighs 917 grams

Polished Green Opal slab GRN99. oldest agate in the world Dimensions at widest points approximatelyGRN99 Green Opal & Magnesite slab, cut and polished on one side . Dimensions at widest points approximately 90 mm x 70 mm x 11 mm thick Weighs 121 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..