Producer RZA likened it to a Picasso artwork, or an ancient Egyptian artefact.
"It's a unique original rather than a master copy of an album,"
he said when the album went on sale in 2015.
As a result, only a handful of people on the planet have heard snippets of the 31 tracks.
A group of potential buyers and media heard a 13-minute section in 2015, and
disgraced drug firm executive Martin Shkreli - who bought the album for $2m (£1.6m, A$3m) - streamed clips of the music on YouTube to celebrate Donald Trump's 2016 election victory.
