Dating from the period 1968-73, the collection includes posters, flyers, hand written song lyrics, photographs and postcards from Black Sabbath front man Ozzy, who later starred in the hit TV show The Osbournes.
The collection was due to be sold at Sheffield Auction Gallery on September 30 but instead the lots have been sold by private treaty for an undisclosed sum to the family.
Stephen Flintoft, specialist music valuer and auctioneer at the gallery, said the sale “ensures that this important piece of hard rock musical history remains intact”.
The collection was saved by a Sheffield resident from a property being demolished in the old London Docklands in the 1980s. It had an estimate of between £2000-3000.
The British heavy metal band from Aston, Birmingham, were formed as Earth Blues Company (shortened to Earth) in 1968. The following year they changed their name to Black Sabbath, taken from an early 1960s Boris Karloff horror film.
The first two albums – Black Sabbath and Paranoid – laid the foundations for so many heavy metal bands to build on with their killer riffs and extreme volume.
The memorabilia included postcards from Ozzy to his mother in Birmingham, written while on tour, and handwritten lyrics headed 'by Earth' to the song Changing Phases, a title later changed to Solitude, which featured on the 1971 double platinum Black Sabbath album Master of Reality.