Polished fossil Oncolite slab. ONC117 chrysoprase 115 mm x 60 mm

115 mm x 60 mm x 40 mm thick

Eucryptite is a lithium aluminium silicate that occurs in LCT pegmatites

Dimensions approximately 130 mm x 100 mm x 50 mm thick

Weighs 165 grams

Polished fossil Oncolite slab. ONC117 chrysoprase 115 mm x 60 mmONC117. 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. 160 mm x 80 mm x 8. 5 mm thick. Weighs 217 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