Polished fossil Oncolite slab. ONC112 prehnite Very rare fossil stromatolite slab

Very rare fossil stromatolite slab polished on one side

100 mm x 70 mm x 60 mm

Dimensions at widest points approximately 130 mm x 100 mm x 70 mm thick

135 mm x 85 mm x 50 mm thick

Weight :  274 grams

Polished fossil Oncolite slab. ONC112 prehnite Very rare fossil stromatolite slabONC112. 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