The collection will feature over 100 songs from the Man In Black's work with producer Rick Rubin...

A collection of more than 100 Johnny Cash outtakes including a duet with late Clash singer Joe Strummer is set for a possible Christmas release.

The box set is being compiled by legendary producer Rick Rubin, with whom Johnny Cash has worked extensively over the past decade.

Tentatively titled ‘Unearthed’, the American/Lost Highway collection, will probably span five discs, four of which will be made up purely of unreleased material, Rubin told

Johnny Cash[/a]’s past four studio albums, each recorded and produced by Rubin for his American Recordings label.

Rubin says over the past 10 years, he and Johnny Cash have amassed roughly 150 unused songs, including many covers and duets with the likes of Nick Cave and Joe Strummer, both of whom appeared on Johnny Cash‘s 2002 album ‘American IV: The Man Comes Around’. The duet with Johnny Cash was on Johnny Cash‘s ‘Redemption Song’.

Rubin says that since the death of Johnny Cash‘s wife June Carter Cash in May, the 71-year-old country legend has thrown himself into his work and the pair are currently progressing well on their next American Recordings album.

Rubin says: “He kind of made a decision. He called me a couple of days after June passed and said that he really has dedicated his life to work and wants to be busy all the time and focused on songs. That’s what he wants to do, so that’s what we’re going to do that’s what we’ve been doing.”

Rubin also notes that Johnny Cash, who suffers from diabetic neuropathy – a disease of the nervous system that leaves its victims susceptible to pneumonia – is doing well these days, physically.

“He’s been really getting very healthy, and walking more and kind of really seems to be doing better than he has in years,” he says.