Jimi Hendrix, the ultimate guitar god lives on. A new compilation album will include a 40-year-old tune that Hendrix recorded but never released from one of his final studio sessions before his untimely death in Sept. 1970.

The song, “Valleys of Neptune,” will be the title track of the upcoming compilation sharing the same name. It hits shelves March 9th, according to Experience Hendrix LLC, which managed the late singer’s affairs.

The company and Sony Music Entertainment’s Legacy Recordings are using the album to spearhead their monumental 2010 Jimi Hendrix Catalog Project.

Valleys of Neptune will include 12 “fully realized studio recordings,” of more than 60 minutes of music never commercially available on a Jimi Hendrix album, Sony says.

The title song, though never commercially released, appeared on the 1990 four-disc set Lifelines: The Jimi Hendrix Story. It will be released as a single on Feb. 2.

The 12 tracks were recorded during Hendrix’s  last recording sessions. At the time, he was working on a new album  First Rays of the Rising Sun, which was released posthumously.

It features studio versions of Hendrix’s covers of “Bleeding Heart” and Cream’s “Sunshine of Your Love,” as well as rerecorded versions of classics “Fire,” “Red House” and “Stone Free.”

Experience Hendrix Group, now run by Hendrix’s sister Janie, is also reissuing all three of the Jimi Hendrix Experience’s studio albums.

The opening wave of releases will included new deluxe CD/DVD editions of Are You Experienced?, Axis: Bold As Love, Electric Ladyland and First Rays of the New Rising Sun, also available on vinyl, on March 9.

Valleys of Neptune provides an essential, compelling, and up-til-now largely unseen view of what Jimi Hendrix was up to musically in the critical period between the release of Electric Ladyland in October 1968 and the 1970 opening of his own Electric Lady Studios in Greenwich Village.

The state of the art facility is where he would begin First Rays of the New Rising Sun, his final album, according to the company.

“My brother Jimi was at home in the studio. Valleys of Neptune offers deep insight into his mastery of the recording process and demonstrates the fact that he was as unparalleled a recording innovator as he was a guitarist,” Janie says. “His brilliance shines through on every one of these precious tracks.”

Rolling Stone named Hendrix the Greatest Guitarist of All Time.