and "didymos", meaning  twin . Rare-earth magnets ,  lasers , violet colors in glass and ceramics,  ceramic capacitors 61 Pm Promethium for the  Titan   Prometheus , who brought fire to mortals. Nuclear batteries 62 Sm Samarium for  Vasili Samarsky-Bykhovets , who discovered the rare earth ore  samarskite . Rare-earth magnets