Polished fossil Oncolite slab. ONC116 Rhodo x 18 mm thick

x 18 mm thick

170 mm x 55 mm x 9

Box measures 43 cm x 28 cm x 5 cm deep

DO229  Dendritic Opal slab

DOT105  Tumble polished Dendritic Opal

Polished fossil Oncolite slab. ONC116 Rhodo x 18 mm thickONC116. 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. 105 mm x 85 mm x 7 mm thick. Weighs 134 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 in