Polished fossil Oncolite slab. ONC112 prehnite 100 mm x 70 mm

100 mm x 70 mm x 60 mm

OJ194  A slab

Weight :  274 grams

Dimensions at widest points approximately 120 mm x 70 mm  x 7 mm thick

cut and polished  on one side with a natural back and a cut base to stand as a display specimen

Polished fossil Oncolite slab. ONC112 prehnite 100 mm x 70 mmONC112. 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. 145 mm x 105 mm x 8 mm thick. Weighs 285 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