Folorunsho AlakijaNigerian oil tycoon Folorunsho Alakija is now the richest black woman in the world with an estimated fortune of $7.3 billion. Africa boasts 55 billionaires – far more than previously thought – and they’re worth a staggering $143.88 billion in total, according to pan-African magazine Ventures Africa.

Mother-of-four, Folorunsho Alakija, 62, started her career as a secretary in a bank then studied fashion and launched a label but her big break was oilIn 1993, her company, Famfa Oil, was awarded an oil prospecting license, which later became OML 127, one of Nigeria’s most prolific oil blocks

The company owns a 60 per cent stake in the block, valued at around $7.3 billion, Ventures Africa reports

According to Forbes, Oprah Winfrey is worth $2.9 billion

Starting her career as a secretary in a bank in the mid 1970s, Alakija, 62, then studied fashion in London and returned to Nigeria to start a label, Supreme Stitches. But her biggest break came in oil.

In 1993, her company, Famfa Oil, was awarded an oil prospecting license, which later became OML 127, one of the country’s most prolific oil blocks, by then-president Ibrahim Babangida.

The company owned a 60 per cent stake in the block until 2000 when the Nigerian government unconstitutionally acquired a 50 per cent interest without duly compensating Alakija or Famda Oil.

In May 2012, Alakija, a married mother-of-four, challenged the acquisition and the Nigerian Supreme Court reinstated the 50 per cent stake to her company.

She also has a charity called the Rose of Sharon foundation that helps widows and orphans by empowering them through scholarships and business grants.