Umoona Mine
Hutchison street, Coober Pedy, South Australia state, Australia
Occurrence
Opal, chalcedony, and gypsum formed in cracks during weathering and diagenesis processes in the Early Cretaceous Aptian (120 Ma) Bulldog Shale of the Marree Subgroup. The Bulldog Shale was formed under shallow marine environment and produces a lot of fossils. Fossils were replaced by opal during the diagenesis process. The Marree Subgroup overlies unconformably the Late Jurassic Algebuckina Sandstone and Paleozoic sediments.
Outcrop of a vein of precious opal displaying play of color. The pale brown host is weathered shale of the Cretaceous Bulldog Shale.
Reported Minerals
- Opal
Mineral Assemblages
- Opal - Gypsum
- Limonite - Opal
Localities
- Shimo-jinya (Conglomerate, Lithiophorite)
- Mount Orihime (Chert, Lithiophorite)
- Masaka (Chert, Lithiophorite)
- Umoona Mine (Opal deposit)
- Old Timers Mine (Gypsum, Fibrous)
- Opal Quest Mine(Gypsum, Rosette)
- Moon plain (Gypsum, Tabular)
- Jweller's shop noodling area (Chalcedony)