Polished fossil Oncolite. ONC109 Polished rock. TIR146 Tiger Iron rough rock

TIR146 Tiger Iron rough rock

150 mm high  x 90 mm x 55 mm thick

Dimensions at widest points approximately 100 mm x 90 mm x 50 mm thick

245 mm x 100 mm x 11 mm thick

Dimensions approximately 85 mm x 75 mm x 12

Polished fossil Oncolite. ONC109 Polished rock. TIR146 Tiger Iron rough rockONC109. 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