Polished fossil Oncolite slab. ONC115 oldest agate in the world PA277 Pilbara Agate

PA277  Pilbara Agate

DO182  Dendritic Opal rough rock

Weighs 916 grams

The amphibolite

Dimensions at widest points approximately 155 mm x 90 mm x 50 mm thick

Polished fossil Oncolite slab. ONC115 oldest agate in the world PA277 Pilbara AgateONC115. 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