Dia Beacon is the museum for the Dia Art Foundation's collection of art from the 1960s to the present and is one of the 12 locations and sites they manage. From Wikipedia
The cause of death was heart failure, as confirmed by Arne Glimcher, Founder and Chairman of the international Pace Gallery, which has represented Irwin's work since 1966. With a career that spans over a century, Irwin's work reoriented how viewers perceive space, pushing boundaries within minimalism and abstract expressionism.