Polished Marble Bar Chert slab MB114 Opalite Dimensions at widest points approximately

Dimensions at widest points approximately 310 mm x 210 mm x 16 mm thick

Dimensions at widest points approximately 200 mm  x 105 mm x 9 mm thick

An unusual feature of some pieces are septarian structures with black colouration

OJ191  A slab

Polished Marble Bar Chert slab MB114 Opalite Dimensions at widest points approximatelyMB114 Marble Bar Chert slab polished on one side . Dimensions at widest points approximately 140 mm x 90 mm x 9 mm thick. Weighs 188 grams. Marble Bar chert is a finely banded, iron rich silica rock from the Marble Bar Chert Member (Warrawoona Group) of Western Australia. Formed in shallow Archean seas, it dates to the Paleoarchean (~3. 46 billion years old), making it one of the Earths oldest well preserved sedimentary rocks. From near the town of