Opal pseudomorphs from White Cliffs, New South Wales

Abstract

The occurrence of Opal at White Cliffs as pseudomorphic crystals, called locally "fossil pineapples" has been known for some time; they have been described by several observers, but no agreement has yet been reached as to the species of the original mineral. Recently several good specimens have reached Sydney and were examined by Professor T. W. E. David and the authors, the conclusions arrived at being set forth in the present paper.