A Canadian cryptocurrency exchange has bought four golden casts of the hands of former South African president Nelson Mandela for $10 million worth of bitcoin.

Arbitrade has purchased what's believed to be the last surviving life-size impressions of Mandela's hands, each made out of nine kilograms of pure gold.

Mandela served as president of South Africa from 1994 to 1999, after having been released from prison in 1990 following a 27-year sentence. The casts were made in 2002 as part of a plan to make 27 gold impressions of Mandela's hands, one for each year of his incarceration.

But the collection was never completed, and the other versions of his hands were ordered destroyed by the man himself. He died in 2013.

The seller is Malcolm Duncan, a South African businessman now living in Calgary, who knew Mandela.

In a press release, Arbitrade says the company shares Duncan's "deep admiration for Mandela," but they are also making the purchase because of the connection to gold itself.

The company plans to release five new cryptocurrencies that will be backed by precious metals such as gold. Bitcoins and other cryptocurrencies use encryption techniques to regulate the generation of units of currency and verify the transfer of funds

"The artifacts celebrate not only the remarkable contributions of Nelson Mandela to humanity each year, but also all that has been done by South Africa in supporting gold and the mining industry though the years," Arbitrade said.

The company says it plans to exhibit the hands at museums around the world.

In addition to being a cryptocurrency exchange, Arbitrade also mines for its own cryptocurrencies, and is soon to open Canada's largest cryptocurrency mining facility in Watford, Ont., which will have 65,000 mining rigs when it's up and running.