Oil and gas company Range Resources will voluntarily disclose information on the chemicals it uses to harvest natural gas from an eastern U.S. rock formation.

Range, whose leases cover 1.3 million acres of the Marcellus Shale, uses a process called hydraulic fracturing, which forces a mixture of water, sand and chemicals into the formation to break up rocks and extract natural gas.

The company plans to provide information about the chemicals used at each of its well sites to the Pennsylvania Department of Environmental Protection (DEP) and on its website, including the chemicals' classifications, how much of each chemical is used, dilution factors and their specific and common uses.

Range says it uses four chemical additives and that they make up 0.14 percent of the fluid used in hydraulic fracturing. Water and sand make up the rest of the mixture.

"Last month, DEP took the lead on this initiative by becoming the first state environmental agency in the country to post a comprehensive list of additives used in surface and fracturing operations - online, in one place, in full view of the public," said DEP Secretary John Hanger in a statement. "Today's announcement that Range intends to go even further on this issue is welcome news, and represents a model that other operators in the Marcellus must follow without further delay."

_{Natural gas drilling - CC license by Ruhrfisch}