Jet is a great lightweight black stone that is great for jewelry because it is very lightweight. Here is some information from Wikipedia about what it is and Where it is from: Jet is a product of high pressure decomposition of wood from millions of years ago, commonly the wood of trees of the family Araucariaceae. Jet, found at Whitby, in England, is of early Jurassic (Toarcian) age, approximately 182 million years old. Whitby Jet is the fossilized wood from species similar to the extant Chile pine or Monkey Puzzle tree (Araucaria araucana). We have some great tumbled shapes that would work in all kinds of projects – Email us with questions! Thanks for looking!