Jet Jewellery and Ornaments by Helen Muller, Shire Publications, Ltd., 32 pages, 2003. These pieces are about 2 centimeters in size and produce a brown streak. They show the "rounded" shape and matte luster of jet that is collected along the beach. Jet found by beachcombing: Two pieces of Whitby Jet found by beachcombing along the eastern shore of England. Some specimens display obvious plant structures without magnification. The woody origin of jet has been confirmed because, when examined under magnification, jet contains the preserved cellular structure of the original woody plants. This gives the jet a more uniform texture and a toughness that contrasts with the friability of coal removed from a seam. As the jet is transformed into a rock, it does not develop a system of fractures, known as "cleat," which develops in a coal seam. Jet is thought to absorb oils released by the decay of oil-rich organic debris in the surrounding rock, such as algae and plankton. This produces a material that is similar to coal however, this material is much more influenced by the geochemical environment of the surrounding organic-rich shale.
It is then compacted, degraded, and heated in isolation. Instead, it forms when an individual piece of woody material such as a tree branch is washed into a body of water, becomes waterlogged, sinks to the bottom and is covered by organic-rich sediment. Most coal seams form when a swamp containing abundant woody material is buried that woody material is then compacted, undergoes organic degradation, and is heated. The material known as "jet" is very similar to coal, but the way that it forms is different.
0 kommentar(er)
