Gallium, GAL ee uhm, is a soft, silver-white metal found throughout Earth's crust. Its general properties resemble those of aluminum. Intermetallic compounds (compounds of two or more metals) with gallium are used as high-temperature rectifiers; as semiconductors in transistors, light-emitting diodes, and semiconductor lasers; and in memory devices in high-speed computers. Gallium remains in liquid form over a larger temperature range than does any other element. It was first used to fill high-temperature thermometers. A mixture of tin, silver, and gallium is used in dental fillings. It is found in various ores, rocks, and minerals, such as diaspore, sphalerite, germanite, bauxite, and coal.