Africa has two new billionaires on the block, both of whom are black.But Africa's richest men, according to the Forbes rich list, remain two white South Africans who inherited their wealth.They have now been joined by a Nigerian industrialist who seems to be in every industry going and a black South African mine magnate. But with only four entries on the list Africa remains the continent with the fewest mega-rich citizens.You need at least $1.3bn to get in, and there are currently 1062 on the list.New entrant Aliko Dangote is Nigerian and has built a $3.3bn fortune from a loan from his uncle.In a little over 25 years, Mr Dangote has built an empire that includes the number one sugar production company in the country, a cement factory and a virtual monopoly on the production of pasta in Nigeria.His company bought two refineries in the last days of the regime of Olusegun Obasanjo, but the sale was cancelled by the new president Umaru Yar'Adua, after allegations that due process was not followed.Last year Mr Dangote told the BBC about his close connections with government."If we don't have the right people there then [all the] money I have is useless. If the country turns into another Zimbabwe, for example, then I will become a poor person," he said.The second newcomer is South African Patrice Motsepe. The lawyer, who bought several unprofitable gold mines and turned them round, now has a fortune of $2.4bn.Born in the township of Soweto, he moved from being the first black partner at Bowman Gilfillan law firm in Johannesburg to running a mining contract firm after Apartheid collapsed.His African Rainbow Minerals now has annual sales of $875 million. Forbes says Mr Motsepe took full advantage of the Black Economic Empowerment laws that require mining firms to be over a quarter black-owned.Two white South Africans remain on the list: Nicky Oppenheimer and family own De Beers and are worth $5.7bn.Johann Rupert and his family head Swiss luxury goods group Richemont.This includes the Cartier label and their fortune has dipped to $3.8bn.Source: BBC