1.4" Polished Common Opal & Chalcedony Nodule Pair - California

This is a cut and polished nodule of common opal, chalcedony, and chert. It comes out of the Otay Formation, located on Rolling Hills Ranch in San Diego County, California. This formation contains preserved fossils of the Oligocene to Miocene periods, along with some mineral formations like this nodule. Both halves of the nodule are included.

It was collected May, 2012 by Angela Ravenscroft.