Dickens died April 22 at a Washington, D.C., hospice of complications from pneumonia, said Ken Irwin, a founder of Rounder Records, her longtime label.
Dickens became a fixture on the bluegrass circuit in the 1960s and '70s with her musical partner, Alice Gerrard, and continued as a solo artist. She also was highly respected as a folk and country musician.
"She is one of the absolutely finest and authentic singers we have," Charles Wolfe, music historian and author of the 2001 book "Classic Country: Legends of Country Music," told the Washington Post in 2001. "Her singing has not only that 'high lonesome sound' but you can hear the pain and anguish and anger in it. It is absolutely heartfelt and sincere."
Hazel Jane Dickens was born June 1, 1935, in Montcalm, W.Va., and raised in poverty, the eighth of 11 children. Her father delivered timber to coal mines and was a Primitive Baptist minister. Musical instruments were not allowed inside the church.
"You learn to listen to the lyrics and to the melody," she told the Charleston (W.Va.) Gazette in 1996. "I never thought about it until I got away from home. I used to feel instruments got in the way of listening to the melody and the lyrics. I think it's very beautiful to hear that many voices, untrained, singing from the heart and soul."
She moved to Baltimore as a teenager. "We really didn't have anything at all" growing up in West Virginia, she told the Washington Post in 1981. "When you got big enough, you got out and supported yourself or you stayed and had nothing."
In the 1950s Dickens met and started performing with Mike Seeger, the half brother of folk singer Pete Seeger. Her association with Mike Seeger led to her teaming with Gerrard. Dickens continued as a solo artist after she and Gerrard dissolved their partnership in the mid-1970s.
Dickens "was writing country songs about women's concerns long before anyone else in Nashville was doing it," country music historian Bill Malone told the Washington Post in 2001. Irwin said Dickens was "concerned for social justice for all. Some people tried to classify her as a feminist, but she always thought she was a humanist."
Her music was featured in "Harlan County, USA," Barbara Kopple's 1976 Oscar-winning documentary about Kentucky coal miners. She also appeared and sang in "Matewan," John Sayles' 1987 film about labor organizing in a mining town.
"I've never lost my sympathy for working people," she told the Chicago Sun-Times in 2002. "I've always said that if I have a religion, it's the working-class experience and what I feel for working-class people."
Her many honors included a National Heritage Fellowship from the National Endowment for the Arts. A tribute album is being prepared with artists such as Emmylou Harris, Linda Ronstadt and the Judds performing Dickens' songs. A new album by Dickens is close to being released.
She was divorced, and a brother was her only immediate survivor.