Polished Green Opal rock GREEN76 magneprase 180 mm x 105 mm

180 mm x 105 mm x 40 mm thick

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

145 mm x 90 mm x 9 mm

The environment they grew in was possibly freshwater algal marshes

170 mm x 100 mm x 9 mm

Polished Green Opal rock GREEN76 magneprase 180 mm x 105 mmGREEN76 Green Opal & Magnesite rough rock, cut and polished on one side with a rough, naturally weathered back Dimensions at widest points approximately 130 mm x 130 mm x 50 mm thick Weighs 1,238 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.