Hickel died of natural causes at Horizon House, an assisted living facility in Anchorage, according to longtime Hickel assistant Malcolm Roberts.
Hickel was dismissed from his Interior post in late 1970, several months after he wrote Nixon a letter critical of the president's handling of student protests following the National Guard shootings at Kent State and the US invasion of Cambodia.
"I believe this administration finds itself today embracing a philosophy which appears to lack appropriate concern for the attitude of a great mass of Americans - our young people," began the letter, which helped stir the national debate about the growing generational rift over the Vietnam War.
When Hickel was fired in November 1970, Nixon spokesman Ron Ziegler said Nixon took the action because his relationship with Hickel lacked "essential elements of mutual confidence." Hickel had never held elected office when he upset two-term Democrat Gov. William Egan in 1966.
Hickel resigned in 1969 to become Interior secretary with the Nixon administration where he quickly made national headlines as the environmental movement began to take root in America.
Hickel imposed stringent cleanup regulations on oil companies and water polluters after an oil rig explosion off the coast of Santa Barbara, Calif. He also fought to save the Everglades from being destroyed by developers and advocated for making Earth Day a national holiday.
An "Alaska boomer" with complex views on environmentalism and developing the state's oil-rich resources, Hickel railed against "locking up" the Arctic National Wildlife Refuge from oil drilling and used settlement money from the Exxon Valdez oil spill lawsuit to help repair Prince William Sound.
He frequently described Alaska as an "owner state" and advocated that the state's wild frontier should be developed responsibly to preserve its value.
Days before he was fired by Nixon, Hickel had told CBS' "60 Minutes"» that he would not quit the Interior post under pressure. He said he would only go away "with an arrow in my heart, not a bullet in my back." Hickel's political career started in the early 1950s as a crusader for Alaska statehood, both at home and in Washington. He was also involved in the Alaska Native Claims Settlement Act which helped pave the way for the trans-Alaska oil pipeline.
Hickel's was a quintessential Alaska rags-to-riches story.
