Polished Green Opal slab GRN86 #google The interesting cylindrical cavity is

The interesting cylindrical cavity is all that remain of a fossil belemnite which was a squid-like creature with a tapering torpedo or bullet shaped body

100 mm x 50 mm x 30 mm thick

Dimensions at widest points approximately 110 mm x 70 mm x 55 mm thick

Interesting reddish colours

Polished Green Opal slab GRN86 #google The interesting cylindrical cavity isGRN86 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.