Jet Lignite is a mineral with a hardness of 3 out of 10 on the Mohs scale of mineral hardness [?]. These Amorphously structured gems are made of a variation of things, their full chemical compound being unknown. Jet is an organic gem material composed of lignite, and is a bituminous coal which can be polished. It is compact, homogeneous, has a hard, glossy surface and black interior variety of fossilized lignite or coal. It is an opaque black coalified fossilized drift wood from the coniferlike, 180 million years old Araucaria or monkey puzzle tree that has been dried and fractured following death of the tree; thus causing some of its woody structure. This wood was subsequently transported downriver by floods, during which sand grains entered shrinkage cracks and fractures in the wood, before becoming waterlogged and sinking into the black mud of the seafloor. Jet is so effectively fossilized (by carbon replacement) that a thin section can readily reveal precise structural details of the crushed original wood that was the source of this essentially Victorian organic gem material. It has an amorphous crystal system, and has a color of black or dark brown, and is opaque, with conchoidal fracture. It has a velvety waxy luster, sometimes with pyrite inclusions and, when rubbed, becomes electrically charged. Much was found in England (Whitby, Yorkshire), but today it comes from Spain (Asturias), France (Aude Departement), the USA (Colorado, Utahs Henry Mountains, New Mexico), Russia, Poland, India, Turkey, China, Spain, Germany (Wurttemburg), and Cambodia. Of these deposits only the British and Spanish deposits have been worked commercially. Jet is warm to the touch, light in weight, induces electricity when rubbed on wool or silk. It burns readily with a sooty blue flame. Imitations are black tourmaline (schorl), black andradite (melanite), black zircon, albertite, Kimmeridge shale, bog oak, horn, lignite, shale, vulcanite a hardened rubber, black-dyed chalcedony is called black onyx. Other jet imitations are made of glasses and obsidians. A type of black glass material is known as Paris jet. It can be distinguished from other black stone or material simulants by touching its surface with a heated needle, which releases an odor of coal, or when it is rubbed, it gives off a strong odor. Misnomerly called black amber or referred as black turquoise. Sometimes applied to a black marble. Also called scorpion stone, jet coal, gagate, agstein. Also spelled jett. Jet is often confused with lignite, cannel coal, and shale. - See more at: gem5/stone/65/jet-lignite/#sthash.wkwtEWR5.dpuf
Posted on: Mon, 13 Oct 2014 21:07:39 +0000