West Performing in the Relix office in 2016

Leslie West, best known as the co-founder and lead guitarist of hard rock band Mountain, passed away on Wednesday. He was 75 years old.

According to a statement from a spokesman Steve Karas, the cause of death was cardiac arrest. According to Rolling Stone, West suffered cardiac arrest on Monday at his home in Daytona, Fla. He was rushed to the hospital but never regained consciousness.

West had dealt with various health problems later in his life. He battled bladder cancer in the early 2000s, and in 2011 he had his lower right leg amputated due to complications with his diabetes. However, less than a year after the amputation, West was back to performing onstage, a testament to his tenacity.

Leslie West was born Leslie Weinstein on Oct. 22, 1945 in New York City, though he grew up in the suburbs. He was first given an instrument at age 8, when his mother bought him a ukulele. After receiving money as gifts for his Bar Mitzvah, West purchased himself a guitar.

In the mid-to-late ’60s, West began playing with an R&B/soul-rock influenced band called the Vagrants. Some of the band’s work was produced by Felix Pappalardi, who was also working with Cream on Disraeli Gears. After West and Pappalardi met through the Vagrants, they formed pioneering hard rock band Mountain in 1969.

One of Mountain’s very first gigs was at 1969’s Woodstock Festival. Shortly after, original drummer N.D. Smart left the band, replaced by Corky Laing. In February of 1970, the band would release their most well-known track, “Mississippi Queen,” which featured West’s signature thick guitar tone and meaty vibrato, as well as his unique voice. “[Mississippi Queen] has just everything you need to make it a winner,” West said in an interview Guitar Player this summer. “You’ve got the cowbell, the riff is pretty damn good, and it sounds incredible. It feels like it wants to jump out of your car radio. To me, it sounds like a big, thick milkshake. It’s rich and chocolatey. Who doesn’t love that?”

In 1972, Mountain disbanded. This led to West and Laing forming a power trio with Cream bassist Jack Bruce, called West, Bruce and Laing. Mountain would reform in 1973, only to break up again in ’74. After 1981, the band would frequently reunite for tours.

Throughout his career, West worked with such musicians as Bo Diddley, Joe Bonamassa and Ozzy Osbourne. He was revered by fellow guitarists; in a 2011 interview with Rolling Stone, Eddie Van Halen cited West as among his biggest influences, along with Deep Purple’s Ritchie Blackmore. “Leslie West has this incredible tone,” he said.

Warren Haynes posted a lengthy statement to his social media upon learning of West’s death. “Leslie’s style as a guitar player was not only powerful but unique as well,” he wrote. “He had warm, rich tone and a beautiful, wide vibrato that sounded like a human voice. That combined with his note selection and spacious phrasing really gave him that vocal-like quality that I’ve always personally been drawn to.”

“I know there are some young guitar players out there playing a million notes that may not have listened to Leslie West,” he concluded. “Do yourself a favor and check it out. You’ll be glad you did.” Read Haynes’ full note here.

In 2016, West visited the Relix office and performed Curtis Mayfield’s “People Get Ready.” Watch his performance here.