Polished fossil Oncolite slab. ONC114 beryl Dimensions at widest points approximately

Dimensions at widest points approximately 80 mm x 55 mm x 40 mm thick

DO173  Dendritic Opal slab

Dimensions at widest points approximately 90 mm x 75 mm x 8 mm thick

KO106  Killaloe Opal slab

One edge slightly unpolished

Polished fossil Oncolite slab. ONC114 beryl Dimensions at widest points approximatelyONC114. 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 100 mm x 7. 5 mm thick. Weighs 241 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