Polished Green Opal rock GREEN76 magneprase 145 mm x 90 mm

145 mm x 90 mm x 9 mm

Dimensions at widest points approximately 170 mm x  120 mm x 20 mm thick

The environment they grew in was possibly freshwater algal marshes

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

Polished Green Opal rock GREEN76 magneprase 145 mm x 90 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.