Woogie Posted July 21, 2020 Share Posted July 21, 2020 Hello hello, recently i bought some opal, in amongst the small stones was this. I am wondering if this is a fragment of bone? Maybe a piece of jaw bone? Its from Coober Pedy, which i believe is cretaceous and marine Link to comment Share on other sites More sharing options...
Woogie Posted July 21, 2020 Author Share Posted July 21, 2020 Link to comment Share on other sites More sharing options...
jpc Posted July 21, 2020 Share Posted July 21, 2020 tough to tell from the photos... 1 Link to comment Share on other sites More sharing options...
Darktooth Posted July 21, 2020 Share Posted July 21, 2020 We really need some close-up pics. 1 I like Trilo-butts and I cannot lie. Link to comment Share on other sites More sharing options...
Woogie Posted July 24, 2020 Author Share Posted July 24, 2020 Ok, hope these are ok, difficult getting decent close ups. 1st pic, looks like they might be teeth sockets Link to comment Share on other sites More sharing options...
Woogie Posted July 24, 2020 Author Share Posted July 24, 2020 Hard to see, but in the last picture you can just about see its hollow and the matrix runs through it Link to comment Share on other sites More sharing options...
daves64 Posted July 24, 2020 Share Posted July 24, 2020 That may be some of the clay/sandstone it's formed in. A lot of the opals have pockets and/or layers of it in them. 1 Accomplishing the impossible means only that the boss will add it to your regular duties. Link to comment Share on other sites More sharing options...
Woogie Posted July 26, 2020 Author Share Posted July 26, 2020 On 24/07/2020 at 7:12 PM, daves64 said: That may be some of the clay/sandstone it's formed in. A lot of the opals have pockets and/or layers of it in them. Sorry, i am not great at wording things! Im with you though, this came with about 50 other small pieces, most are bits of bi-valve shell i think, some quite interesting looking with holes filled with the matrix, this piece was different though. The holes look like they might be teeth sockets, but the shape of the holes make me think it might not be, especially as it would be marine, i would imagine circular holes? Also it is hollow, like i would imagine a fossil bone to be, dont know if a jaw bone would be hollow though? Or a piece of shell? Spent a while searching google but cant find anything like it Link to comment Share on other sites More sharing options...
Johannes Posted July 28, 2020 Share Posted July 28, 2020 Congrats, this is a piece of a heterodont lower jaw bone of a cretaceous mammal. Rarer than reptile finds in opal. edit: you may contact Michael Archer, who described the oldest mammal finds of Australia: https://www.researchgate.net/profile/Michael_Archer2 https://www.bees.unsw.edu.au/our-people/michael-archer 3 1 Link to comment Share on other sites More sharing options...
Woogie Posted July 28, 2020 Author Share Posted July 28, 2020 7 hours ago, Johannes said: Congrats, this is a piece of a heterodont lower jaw bone of a cretaceous mammal. Rarer than reptile finds in opal. edit: you may contact Michael Archer, who described the oldest mammal finds of Australia: https://www.researchgate.net/profile/Michael_Archer2 https://www.bees.unsw.edu.au/our-people/michael-archer That is awesome, thank you very much @Johannes I will email Michael Archer to see what he thinks and update Thanks again Link to comment Share on other sites More sharing options...
rodrex Posted September 11, 2021 Share Posted September 11, 2021 Hi All, Could be fish. some fish from the cretaceous have sockets like that. Link to comment Share on other sites More sharing options...
Tetradium Posted September 11, 2021 Share Posted September 11, 2021 10 hours ago, rodrex said: Hi All, Could be fish. some fish from the cretaceous have sockets like that. Doubtfully. Opals tend to develops in tropical land environments. After all opals is a form of quartz with water incorporated into it which requires a lot of leaching of minerals and plentiful rains to make them. Link to comment Share on other sites More sharing options...
jpc Posted September 11, 2021 Share Posted September 11, 2021 2 minutes ago, Tetradium said: Doubtfully. Opals tend to develops in tropical land environments. After all opals is a form of quartz with water incorporated into it which requires a lot of leaching of minerals and plentiful rains to make them. Hmmmm... most of the opalized fossils I have seen are clams, belemnites... and a plesiosaur at Lightning Ridge. Not very land-based. Link to comment Share on other sites More sharing options...
Tetradium Posted September 11, 2021 Share Posted September 11, 2021 Just now, jpc said: Hmmmm... most of the opalized fossils I have seen are clams, belemnites... and a plesiosaur at Lightning Ridge. Not very land-based. Ok sorry about that. Link to comment Share on other sites More sharing options...
Tetradium Posted September 11, 2021 Share Posted September 11, 2021 3 minutes ago, Tetradium said: Ok sorry about that. 3 minutes ago, jpc said: Hmmmm... most of the opalized fossils I have seen are clams, belemnites... and a plesiosaur at Lightning Ridge. Not very land-based. The beautiful opal is formed from rain. There is some conjecture on how exactly this precious gemstone forms, but many believe it is formed when water from rain seeps down into crevasses in the rock. Once the water evaporates, the silica that is left behind dries out and hardens into precious opal. Hmmm you are right about marine sediments exposed on land as well too. And another thing I was wrong about - can be found in Czech Republic as well too so not tropical. Guessing there are still unsolved mysteries about why opals are not widespread. Link to comment Share on other sites More sharing options...
DPS Ammonite Posted September 11, 2021 Share Posted September 11, 2021 (edited) Opal is unstable over geologic time because it dehydrates and dissolves or turns into microcrystalline forms of quartz such as chalcedony and chert. In the US, most precious opal deposits are found in non tropical desert or semi arid areas such as Nevada, Arizona, Idaho, California, Washington and Oregon. Louisiana is an exception. Because opal is young and tends to form in non tropical conditions with shifting water levels, the climate in which it is formed is related to the current semi arid to desert climate. Opal is commonly related to recent volcanic eruptions with silicic ash where the silica is easily mobilized into the water table. Edited September 11, 2021 by DPS Ammonite 2 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
rodrex Posted September 14, 2021 Share Posted September 14, 2021 just some that might help with the opal deposits fauna and geology. 1518330367_AreviewofAustraliasMesozoicfishes-2.pdf Link to comment Share on other sites More sharing options...
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