Jet (lignite)
From Wikipedia, the free encyclopedia
Jet is a geological material that is not considered a mineral in the true sense of the word, but rather, a mineraloid derived from decaying wood under extreme pressure, thus organic in origin. The name "jet" is the English word derived from the French “jaiet”. Jet is black or dark brown but may contain pyrite inclusions, which have a brassy color and metallic lustre.
Jet is found in one of two forms, hard and soft. "Hard" jet is the result of the carbon compression and salt water; "soft" jet is the result of the carbon compression and fresh water. Jet is easily polished and has been used in the manufacture of jewellery, according to the Whitby Museum, dating to 10,000 BC in certain portions of modern day Germany. The adjective jet-black is perhaps more well-known than is this mineral from which it is derived.
Jet as a gem material was highly popular during the reign of Queen Victoria, during which the Queen wore Whitby jet as part of her mourning dress. Jet was popular for mourning jewellery in the 19th century because of its sombre color and modest appearance, and it has been traditionally fashioned into rosaries for monks. In the United States, long necklaces of jet beads were very popular during the 1920s, or Roaring Twenties, when women and young flappers would wear multiple strands of jet beads stretching from the neckline to the waistline. In these necklaces, the jet was strung using heavy cotton thread; small knots were made on either side of each bead to keep the beads spaced evenly, much in the same way that fine pearl necklaces are made. Jet has also been known as black amber, as it may induce an electric charge like that of amber when rubbed. Powdered jet added to water or wine was believed to have medicinal powers.
Although now much less popular, authentic jet jewels are valued by collectors. Anthracite (hard coal) and vulcanite are similar materials that have been used to imitate fine jet: these imitations are not always easy to distinguish from the real thing. Unlike black glass which is cool to the touch, jet is not, due to its greater insulating properties. Also, the structure of jet (which is remarkably like the wood that it is derived from) can be seen under 120X or greater microscopes.
