Lanthanum is a rare-earth metal with chemical symbol La, and an atomic weight of 57. Lanthanum is the first element in the lanthanide series.
Lanthanum is one of the more reactive rare earth metals. It reacts slowly with cold water, and very quickly with hot water. It will also react with elemental halogens, chalcogens, as well as carbon, phosphorus, nitrogen, silicon, and boron.
Lanthanum is a silvery white metal that tarnishes quickly in contact with air. It is a very soft metal and can be cut with a knife.
Lanthanum is readily available from source such as Metallium and eBay.
It is difficult to prepare lanthanum metal in an amateur setting, though a method for making rare earth metals, involving reducing the fluoride with calcium metal, is being developed by the sciencemadness community.
Lanthanum metal will react with water to produce hydrogen, which is flammable. Lanthanum compounds are thought to be non-toxic, however not much research has been done on the toxicity so they should be handled with care.