Lanthanum Hexaboride (LaB6, also called Lanthanum Boride and LaB) is an inorganic chemical, a boride of lanthanum. As refractory ceramic material that has a melting point of 2210 °C, Lanthanum Boride is highly insoluble in water and hydrochloric acid, and converts to the oxide when heated (calcined). Stoichiometric samples are colored intense purple-violet, while boron-rich ones (above LaB6.07) are blue. Lanthanum Hexaboride (LaB6) is known for its hardness, mechanical strength, thermionic emission, and strong plasmonic properties. Recently, a new moderate-temperature synthetic technique was developed to directly synthesize LaB6 nanoparticles.