Opal replacing a Fossil Clam

specimen number:
2063863

location:
Coober Pedy, South Australia, Australia

description:
A mostly complete fossilized clam, this now replaced by translucent opal. This is non-lustrous, a neat little specimen. The specimen comes with a previous label from the collection of Ray DeMark.

Located in the arid interior of South Australia, Coober Pedy is renowned for its vast opal fields situated within Cretaceous sedimentary rocks of the Great Artesian Basin, where silica-rich fluids percolated through porous sandstone and opalized organic remains over millions of years. Commercial opal mining began after the First World War, transforming the remote outback settlement into the primary global source for precious gem-grade opal. Within these shallow underground workings, miners and collectors occasionally uncover remarkable replacement fossils where precious opal has completely substituted ancient marine shells. These rare opalized clam fossils preserve delicate exterior growth lines and internal structures in brilliant flashes of spectral color, making them highly prized among both fossil and mineral collectors.

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