Polished fossil Oncolite. ONC111 #brecciated A trade name for metamorphosed

A trade name for metamorphosed magnesian tholeiite (basalt)

From near Yalgoo

PU133  Purple Chalcedony slab

170 mm x 125 mm  x 9 mm

The quartz epidote axinite mineralisation was evidently caused by hydrothermal activity related to the doleritic sills which are in close proximity to the occurrence

Polished fossil Oncolite. ONC111 #brecciated A trade name for metamorphosedONC111. 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. 140 mm x 100 mm x 6. 5 mm thick. Weighs 204 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