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CHARLESTON, W.Va. -- Renowned environmentalist and mountaintop removal opponent Larry Gibson died of a heart attack Sunday afternoon while working on Kayford Mountain -- the place he dedicated his life to protecting.

Gibson spent decades rallying against the coal industry's impact on Appalachia and was named one of CNN's "Heroes" in 2007. He appeared on ABC's 20/20, traveled the country speaking out against mountaintop removal mining and testified before the United Nations with his signature slogan "Love 'em or leave 'em, just don't destroy 'em."

Just this year, Gibson, 66, traveled to South America to speak about environmental issues.

"I've never met anyone as courageous Larry Gibson. He was a true icon in this work and showed his love for the mountains through action. He didn't sit around and simply enjoy the mountains. He worked everyday to protect them," said Janet Keating, executive director of the Ohio Valley Environmental Coalition. "He died today doing what he loved, which was being on that mountain."

Kayford Mountain, in Raleigh County, was Gibson's birthplace and the final resting place for his ancestors stretching back to the 18th century. Since mining began on the mountain in 1986, Gibson has fought to preserve his home and the homes of others.

Keating worked with Gibson for more than 20 years and stood beside him when he walked across the state during the '90s to promote awareness of the state's mountaintop-removal controversy.

"I can't count how many times he was arrested for fighting what he believed in. We would tell him it wasn't safe and that tensions were high. But it didn't matter. He would say, 'We have to tell people what's happening.' He was tenacious," she said. "In spite of difficult issues, he kept a sense of humor and could lift us up when we were feeling really discouraged about the work."

Friends say Gibson was hospitalized last week and received four stents in his heart.

Bill Price, environmental justice coordinator for West Virginia's Sierra Club, said in the 12 years he spent working with Gibson, he rarely saw him without his bright neon t-shirt and hat broadcasting his message.

"He took simple tools and used them to engage people in the fight for justice in Appalachia. He told his story in a away that just captivated people," Price said. "After people met Larry, they never thought of things the same."

A private funeral is planned, and Larry's family has requested that those wishing to express condolences make donations to the Keeper of the Mountains Foundation, which he founded in 2004 to support mountain communities.

Larry is survived by his wife, Carol, two sons Cameron and Larry Jr. and his daughter, Victoria.

A public memorial service will be announced at a later time.

"Larry used to say, "My mother gave me birth, but the Earth gives me life', " Keating said. "He was profound."

To make a donation, visit mountainkeeper.blogspot.com.