1. Composition and formation mode: Obsidian is a kind of volcanic glass, which is mainly formed by rapid cooling of volcanic magma, and its main component is silicate. The jet belongs to a seasonal variety, and its main component is silicate, which was formed in the deep crust through mineral changes at high temperature and high pressure.
2. Color and appearance: Obsidian is usually dark black, grayish black or dark brown, with a smooth and shiny surface and a special layered structure on the fracture surface. Jet has many colors, such as dark green, black, gray and so on. , dense and hard texture, good luster.
3. Hardness and density: the hardness of obsidian is relatively low, about 5-6, and the density is relatively light; The hardness of jet is relatively high, about 6.5-7, and its density is also relatively high.
4. Origin and use: Obsidian is mainly produced in Mexico, the United States and Iceland, and is often used in jewelry, decorations and making knives. Jet is mainly produced in China, Myanmar, Canada and other places, and is also widely used in sculpture, jewelry, toys and so on.