She is survived by two children from her 12-year relationship with Richards; son Marlon, 46, and daughter Angela, 44.
News of her death was formally announced on social media by her close friends, including Stella Schnabel, daughter of American painter and filmmaker Julian Schnabel. No cause of death was revealed.
“I have never met a woman quite like you Anita,” Schnabel wrote. “You showed about life and myself and how to grow and become and exist with it all. The greatest woman I have ever known.”
Pallenberg’s other close friend, Bebe Buell — mother of actress Liv Tyler — paid her own tribute to the star.
“There was none more beautiful, more unique and more inspiring! The official “sixth Stone”… I will love you forever, dearest Anita.”
The actress, born in Italy in 1944, met The Rolling Stones backstage at one of their concerts in Munich, Germany. She began a romance with Brian Jones, but she left him after two years for Richards. She split from Richards in 1980.
Pallenberg and Richards shared a third child, a son named Tara, who died of Sudden Infant Death Syndrome in 1976.