Polished fossil Oncolite slab. ONC115 oldest agate in the world Weighs 654 grams

Weighs 654 grams

OJ192  A rough rock

Dimensions at widest points approximately 160 mm x 100 mm x 45 mm thick

PA277  Pilbara Agate

Polished fossil Oncolite slab. ONC115 oldest agate in the world Weighs 654 gramsONC115. 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. 170 mm x 70 mm x 7. 5 mm thick. Weighs 211 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