Author and environmentalist Peter Matthiessen passed away at the age of 86 on Saturday.
Matthiessen had been dealing with acute leukemia for over a year was sick "for some months," said Geoff Kloske, his publisher with Riverhead Books. The Associated Press reports the writer died in a Long Island hospital.
He was known for both his nonfiction writing and being an avowed environmentalist, which was evident in his works, including The Snow Leopard, which was about his time in the Himalayas. That book, along with Shadow Country won National Book Awards.
His novel At Play in the Fields of the Lord about missionaries struggling to survive in Brazil as they are beset on both sides by mercenaries and natives. A film, starring John Lithgow and Daryl Hannah, was later adapted from the novel.
During his lifetime, Matthiessen helped found The Paris Review, was friends with Cesar Chavez and provided a written defense of Leonard Peltier.
According to The New York Times, he knew many other famous post-World War II writers, such as Kurt Vonnegut, James Jones and E.L. Doctorow.
Matthiessen passed away just days before his latest book, In Paradise, was due to hit bookstores.