Rio Tinto Group said it received partial approval from the Zimbabwean government for its plan to increase ownership of the Murowa diamond mine by black citizens of the country.

AuRico Gold Inc. is paying the cheapest valuation for a takeover of a North American gold producer in seven years even as bullion trades at a record. Including net cash, AuRico’s acquisition valued Northgate at 14.7 times Ebitda. In last year’s biggest North American gold takeover, Toronto-based Kinross, Canada’s third-largest producer of the metal, paid 40.4 times Ebitda to acquire Red Back Mining of Vancouver in a $6.7 billion deal.

Bloomberg reports demand for diamond jewelry in India may slow as a surge in prices discourages buyers. Polished diamond prices, which jumped about 60 percent to 70 percent in the last six months, may gain further in the next few months, said Sandeep Kulhalli, vice president, retail and marketing at Tanishq, the jewelry retail chain owned by Titan. The company is India’s biggest retailer of gold jewelry.

Copper rose the most in more than two weeks on speculation that a strike at the world’s biggest mine may worsen a global supply shortage. A strike at BHP Billiton Ltd.’s Escondida mine entered a fifth day as Chilean labor authorities prepared to mediate talks between union and company officials.

Bloomberg reports nickel is the only base metal traded on the LME to record a decline in its inventories this year. Refined nickel usage exceeded output by 24,000 metric tons in the first half, according to estimates by Barclays Capital.

Australia’s planned carbon tax may reduce the value of the coal industry by about $8.7 billion as producers including Xstrata Plc and Anglo American Plc bear higher costs, according to a research group Wood Mackenzie Ltd. Prime Minister Julia Gillard plans to charge companies an initial A$23 a ton of carbon dioxide from July 2012 before moving to an emissions trading system by 2015. Coal mining companies in Australia, the world’s largest exporter, must pay for fugitive emissions while receiving A$1.3 billion in compensation, with the biggest polluters getting assistance over six years.

Chinese imports rose for the first time in three months in June as buying from overseas became profitable and supply tightened after consumers drained local stockpiles. There are “strong signs” that the country will “come back and buy in a more aggressive way,” according to Codelco, the top producer. Prices slid 3.7 percent in the first six months of the year as demand waned. The metal has gained 46 percent in the past year, reaching a record $4.6575 on Feb. 15.

Caterpillar Inc. said Friday it agreed to form a joint venture with a Chinese transmission manufacturer that will build drivetrain systems and […]