Polished fossil Oncolite. ONC109 polished noreena From the Jeerinah Formation in

From the Jeerinah Formation in the Hamersley Ranges

90 mm x 65 mm x 9 mm thick

Dimensions at widest points approximately 100 mm x 100 mm x 90 mm thick

160 mm x 110 mm x 10

Polished fossil Oncolite. ONC109 polished noreena From the Jeerinah Formation inONC109. Fossil Oncolite polished slab. From the Miocene "Trealla Limestone" north of Carnarvon, Western Australia . Age is approx. 15 million years. Dimensions at widest points approx. 150 mm x 65 mm x 6. 5 mm thick. Weighs 117 grams. Oncolite is a limestone composed largely of oncoidsrounded, coated grains that grow as thin layers of lime mud accumulate around a tiny nucleus (such as a sand grain or shell fragment) under microbial influence. Formed