Both Thornton and Randgold's Chief Executive Officer Mark Bristow are outspoken leaders with strong visions.
"The combination of Barrick and Randgold will create a new champion for value creation in the gold mining industry, bringing together the world's largest collection of Tier One gold assets, with a proven management team", John Thornton, Barrick's executive chairman, said in a statement Monday.
Barrick shareholders will end up own two-thirds of the combined firm and Randgold will own the remaining third.
Bristow acknowledged that the industry has always been criticised for its "short-term focus, undisciplined growth and poor returns".
John Thornton, the former Goldman Sachs executive and executive chairman of Barrick, will become executive chairman of the combined business. Randgold's London listing will be cancelled. This lack of a premium for Randgold shareholders prompted scepticism from some analysts who were also concerned that Randgold's agility could be bogged down by the mammoth Barrick.
As part of the deal, China's Shandong Gold, one of the country's biggest gold producers, has agreed to buy $300 million of shares in Barrick.
Under the all-share deal, Randgold shareholders would be given 6.1280 shares in the combined company for each share they own.
Bristow, a 59-year old trained geologist, has been at the helm of Randgold since its inception in 1995 and is known for his straight-talking, hands-on approach to running the company.
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The all-share deal values Randgold at about US$6 billion.
"UK shareholders are arguably being dealt a poor hand with the merger", said Russ Mould, investment director at AJ Bell.
The price of gold has fallen more than 8% this year, putting all gold producers under pressure.
The new company will have the sector's highest adjusted earnings before interest, tax, depreciation and appreciation and EBITDA margin of almost 50 percent based on 2017 numbers, and the lowest total cash cost position among its peers, the companies said.
The new group will consider selling non-core assets over time.
The deal is subject to approval by the shareholders of both companies, regulatory approvals and other customary closing conditions. Randgold has also slipped this year as it faced labor challenges in the Ivory Coast, a tax dispute in Mali and the prospect of a tougher mining code in the Democratic Republic of Congo.
Barrick's more stable North American assets will reduce Randgold investors' exposure to risky African markets.