On November 29, the Grateful Dead will release the rare, all-acoustic show from April 18, 1970 as a part of Record Store Day’s Black Friday event. The 80-minute, 17-song performance features a combination of original material as well as covers, and concludes with six solo acoustic songs from Pigpen.

The novelty of the show is in the fact that it was once considered lost by longtime Grateful Dead archivist David Lemieux. In a recent interview with Rolling Stone, Lemieux discussed unearthing the historic recording. Recounting the story, Lemieux said he received a call from Carolyn Garcia (“Mountain Girl”) saying she’d found a small box of reels among Jerry Garcia’s belongings. There, in the box, was the tape of this show.

“It’s a show of incredible historical significance,” Lemieux said. “Because it’s the Grateful Dead, but they weren’t billed as the Dead.” The show was originally promoted as Mickey Hart and the Heartbeats and Bobby Ace and the Cards from the Bottom of the Deck, allowing the Grateful Dead a certain amount of artistic freedom. “It’s very rare, it’s unique, and collectors are going to flip out on it,” Lemieux said.

In related news, Lemieux said Grateful Dead HQ has a few items of note planned for the Grateful Dead’s 50th anniversary in 2015 as well as additional releases due out in spring 2014. “People are going to be pretty shocked by what’s to come,” Lemieux promises.