Shares of Barrick Gold Corp. slipped Wednesday after the Canadian mining giant suffered a legal reversal that may affect development of the company's Pascua Lama project on the border between Argentina and Chile.

The company's stock closed down 63 cents, or 1.6 per cent, at $38.87.

Argentina's Supreme Court decided Tuesday to remove injunctions that have blocked key parts of a law to protect glaciers. Barrick argued it shouldn't need to provide the national government with new environmental assessments.

The law requires a thorough inventory of Argentina's glaciers as well as "periglacial" areas where the ice has recently retreated but water remains below the surface. Together, the areas provide much of the country's fresh water.

The law also gives the national government a powerful tool to regulate the mining industry, which until now has been handled by provincial governments whose priorities sometimes clash with people living downstream from the mines.

Barrick maintains that it does not mine on glaciers and that it has already persuaded the provinces it will contain any environmental damage from gold mining, which requires lots of fresh water and a mix of toxic chemicals.

But until now, Barrick's lawsuits have preemptively blocked requirements to provide environmental impact statements to the national government.

Tuesday's ruling could have a major impact on Pascua Lama, the world's highest-altitude gold mine being developed on both sides of the Chile-Argentine border. Barrick said the $5 billion project already has found nearly 18 million ounces of proven gold reserves, more than the company's Veladero mine, another open-pit mine nearby that is already in production.

Groups including Greenpeace Argentina and the Foundation for Environmental and Natural Resources cheered the ruling as a key step. The high court has yet to decide the constitutionality of the overall law, or rule on the environmentalists' requests for an immediate halt to Barrick's high-altitude mining.

Barrick did not immediately comment on Tuesday's decision, but in asking for an injunction against several aspects of the law it said enforcing the measures would unfairly "create a state of uneasiness and uncertainty" surrounding its operations.

The parts of the law Barrick objected to require the national government to define what a glacier is, inventory the remaining glacial and periglacial areas in Argentina, prohibit any activities that destroy glaciers, ban mining in glacial and periglacial areas, and require companies to provide environmental impact statements at the national level.

Rulings by lower courts that blocked those measures were fundamentally flawed, because the requirements provide for the very certainty that Barrick Gold claims it wants, the Supreme Court justices said. The glacier inventory "will make known exactly which areas are protected by law," they wrote.

Barrick and other mining companies as well as the mountainous provinces that directly benefit from their control of the industry have challenged the law on constitutional grounds, saying the national government should have no role in regulating mining. But the justices said that "the law must be applied its constitutional validity is resolved."