An Australian Sauropterygian (Cimoliosaurus), converted into precious opal
Abstract
[Excerpt from first page] The replacement of the calcareous matter in fossils Precious Opal appears to be a fact but little commented on by Authors. The search for opal in the Upper Cretaceous at the White Cliffs Opal-field on Momba Holding, about sixty-five miles north-north- west of Wilcannia, in Co. Yungnulgra, has been signalised by the discovery of many beautiful examples of the entire conversion of the shelly envelopes of Pelecypoda and Gasteropoda, the internal, shells of Belemnites, and Reptilian remains, into Precious Opal by a process of replacement. Many of these are in the Collection of the Geological Survey of N. S. Wales, others have been lent to the same, and through the courtesy of Mr. E. F. Pittman, Government Geologist, I have been permitted to examine them. [etc.]
