👉 The term "feldspars" is a scientific term used in the field of condensed matter physics and solid state physics. It refers to the rare-earth elements, which are found in various materials such as glass, ceramics, and polymers. Feldspar is a type of silicate rock that contains a number of rare-earth elements (such as Y, Ce, Pr, Nd, Sm, V, Rb, and Sr) in its crystal structure. These rare-earth elements have unique properties