Opal Stone – Natural, Specimen, White
Common and precious opal replaced this bivalve's original shell, making it a spectacular fossil. "Opalized fossil bivalve (Bulldog Shale, Lower Cretaceous; Coober Pedy Opal Field, South Australia) 13," photo by James St. John. Licensed under CC By 2.0.
Article: Eight Opal Types Explained
Credit: James St. John
|Natural or man made
|Coober Pedy Opal Field, South Australia
|Play of Color