Refined rare-earth oxides are heavy gritty powders usually brown or black, but can be lighter colors as shown here.Legend: gadolinium · praseodymium · cerium samarium · lanthanum neodymium
photo by Peggy Greb, US department of agriculture/wiki Public Domain
Refined rare-earth oxides are heavy gritty powders usually brown or black, but can be lighter colors as shown here.Legend: gadolinium · praseodymium · cerium samarium · lanthanum neodymium
photo by 보건 이미지 라이브러리 의 (PHIL) 질병 통제 예방 센터/wiki 공개 도메인