Opal starts as silica dissolved in water. When the silica solution fills an empty cavity left by a shell or bone that has rotted away – like jelly poured in a mould – it may harden to form an opalised cast of the original object.
As it turns out, these miners have been uncovering not just opal, but opalized fossils: Bones, teeth, shells and plant material turned to opal, embedded in the ancient claystone and preserved, like the gemstones, for 100 million years under a thin veneer of sediment.
These fossils are literally gems: teeth, bones, shells and pinecones which have turned to solid opal. Australia is the only country where opalised animal fossils are found. Opalised fossils are rare and precious; even more so because in Australia, it is rare to find fossils of any kind from the time of the dinosaurs.
Petrification (petros means stone) occurs when the organic matter is completely replaced by minerals and the fossil is turned to stone. This generally occurs by filling the pores of the tissue, and inter and intra cellular spaces with minerals, then dissolving the organic matter and replacing it with minerals.
Opal is formed from a solution of silicon dioxide and water. As water runs down through the earth, it picks up silica from sandstone, and carries this silica-rich solution into cracks and voids , caused by natural faults or decomposing fossils. As the water evaporates, it leaves behind a silica deposit.
The organic matter or shell breaks down and leaves a cavity where the animal matter was. The sediments that buried animal remains in the opal fields were rich in silica from ancient volcanoes, the silica spheres seep down into the cavity to fill it and the fossils are preserved as silica in the form of opal.
Opalized wood is a type of petrified wood that is composed of opal rather than chalcedony or another mineral material. It almost always consists of common opal, without play-of-color, but rare instances of petrified wood composed of precious opal are known.
Fibrodysplasia ossificans progressiva. Other names. Stone man disease, Münchmeyer disease. The effects of fibrodysplasia ossificans progressiva, a disease which causes damaged soft tissue to regrow as bone.
Bones in which crystals are intimately associated with the collagen fibrils mostly disaggregate into crystal monomers. In dense bones, where the crystals are mostly located between fibrils, they tend to persist as “fused” aggregates. All the crystals are tabular or plate-shaped.
It can take millions of years. As a result, you might skip the coffin. Bones permineralise most rapidly when mineral-rich water can flow through them, imbuing them with things like iron and calcium. A coffin might keep the skeleton nicely together, but it would interfere with this process.
Opalised bones from fields like Coober Pedy, Andamooka and White Cliffs are from plesiosaurs, ichthyosaurs and pliosaurs, which are marine reptiles, not dinosaurs. Fossils are preserved here in silica in the form of opal.
Australia's Opalized Eric
Eric the Plesiosaur. During the natural fossilization process, opalization occurred, leaving the fossil with semi-precious hues of opal colours. This Discovery was made in 1987 by opal miners in Coober Pedy south Australia.
Opals are comprised of hydrated silica and typically contain 6-10% water. They form during the acidic weathering of rocks, or precipitate from water-rich fluids containing silica which fill cracks in rocks.
This happens through a process known as permineralization in which mineral rich groundwater seeps in and replaces the organic tissues of the plant or animal with silica, forming a crystal cast. This is a fairly common type of fossilization, and nearly all petrified wood is formed in this manner.
The colors are so vibrant and alive, and they seem to change depending on how the light hits the opal. Its glow in the dark: The Virgin Rainbow is also known for its ability to glow in the dark. This is due to the presence of a mineral called opalescence, which causes the opal to reflect light in a unique way.
One of the defining aspects of minerals is that they will form crystals; however not all crystals are minerals. Opals, due to how they are formed, lack this crystal structure despite what you might think when gazing at a spectacular crystal Opal specimen.
Dinosaur Bone used in rings and other jewelry is known as gembone (or gem bone) and has been described as one of the most rare and beautiful fossils in the world. Specimens can be traced back to dinosaurs that roamed the earth during the late Jurassic Age around 150 million years ago.
Bone is mostly made of mineral crystals and the protein collagen. While the structure of collagen is well understood, how the minerals in bone – made of hydroxyapatite – are organised is less clear.
Aragonite Crystals Grown on Bones by Reaction of CO2 with Nanostructured Ca(OH)2 in the Presence of Collagen. Implications in Archaeology and Paleontology.
Gembone, also known as gem bone, agatized dinosaur bone, or dinogem, is mineralized bone, often dinosaur bone, which occurs when minerals from groundwater are deposited within the bones. It is one of five gemstones created from organisms (the others being pearl, ammolite, amber and jet).
Stone Man syndrome or fibrodysplasia ossificans progressiva (FOP) is an extremely rare (1 in 2 million) genetic disorder characterised by ectopic ossification of the skeletal and connective tissues leading to progressive fusion of axial and appendicular skeleton.
Minerals may deposit in and around some joints (calcification). This is common around the shoulder. Hip and knee joints may begin to lose cartilage (degenerative changes). The finger joints lose cartilage and the bones thicken slightly.
Check the Stone's Hardness
Opals rank between 5.5 and 6.5 on the Mohs scale, which means they're fairly soft stones. If you can easily scratch the surface of the opal with a knife or other object, it's probably not real.
In Australia, precious opal is found in Cretaceous age sandstones and mudstones. These sedimentary rocks were deeply weathered and this weathering released silica into the groundwater. Small faults and joints in the rocks formed pathways for movement of the groundwater as it penetrated downwards.
Here's the quick answer to what petrified wood is worth. Assuming that the specimens you have are of decent lapidary quality that a buyer would be able to make jewelry out of, you could expect to sell petrified wood between $. 25 and $10.00 per pound.