Minimalist artist whose best-known works included "Stone Field Sculpture" from 1977 and "144 Lead Square" from 1969. His "Lever" was controversial and featured prominently at the 1966 Primary Structures show at New York's Jewish Museum.
He graduated from the Phillips Academy in Andover, Massachusetts, in 1953 and later served in the U.S. Army. He and Hollis Frampton became good friends at Phillips.
He helped organize the Art Workers Coalition in 1969.
He was accused of murder when his wife
He and fellow American artist Tony Smith both produced minimalist sculptures.