earthchild, 29 days ago Opals form in cavities within rocks. If a cavity has formed because a shell was buried in sand or clay that later became rock, and conditions are right for opal formation, then it forms a fossil replica of the original object. https://www.geologypage.com/2017/04/opalised-fossils-form.html #geology photo: https://www.pinterest.com/pin/535506211945205379/
Opals form in cavities within rocks. If a cavity has formed because a shell was buried in sand or clay that later became rock, and conditions are right for opal formation, then it forms a fossil replica of the original object.
https://www.geologypage.com/2017/04/opalised-fossils-form.html
#geology
photo: https://www.pinterest.com/pin/535506211945205379/
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