Fossil Coral x Petrified Wood

Fossil Coral is the common name for the properly called "agatized fossil coral".  Ancient (and I mean ancient - 20-40 million years ago!) corals' calcium-rich skeletons were slowly dissolved by acidic water, and were partially replaced by dissolved silica (quartz) - namely chalcedony (microcrystalline quartz), also known as agate.  The different colours are due to different trace minerals. It is the matte brown-to-red beads you see.   The polished Petrified Wood follows a similar process - water seeping into the ground over countless millions of years slowly replaces the wood with the minerals in the water. It is the shiny, darker hued beads.   Mookaite comes from it being found in the Mooka Creek on the western side of the Kennedy Ranges, Australia.  About 120 million years ago, tiny plankton protozoa organisms called radiolarians lived in what was then a sea bed, and over time with their mineral rich skeletons died and formed radiolarite, a sedimentary rock. This mainly cryptocrys