Magnesite is a cement-like construction material, a compound of magnesium, carbon and oxygen.  Noguchi first used magnesite in his Chassis Fountain  for the Ford Motor Company Pavilion at the 1939 New York World's Fair.  During the 1940s Noguchi also created a number of magnesite sculptures, most notably the self-illuminated works that he called Lunars , whose undulating magnesite surfaces covered hidden light bulbs.