Lutetium Oxide (Lu2O3), also called lutecia, is a cubic compound of lutetium. It is a lanthanide oxide, also known as a rare earth. Lutetium Oxide is white in color and insoluble in water. Due to the nature of oxide compounds, Lutetium Oxide is not conductive to electricity. However, it produces lutetium tantalate, the densest white material known, and is frequently used for x-ray phosphors. It is also insoluble in water solutions and is useful for ceramic applications.