House of Representatives Natural Resources Committee (NRC) chairman Raul Grijalva has proposed legislation that includes an 8% gross royalty on new mining projects, a 4% gross royalty on existing mines on federal lands and a US7c per ton tax for every ton of dirt moved.

The legislation "was aptly described by Ranking Member Bruce Westerman of Arkansas as ‘death by a thousand cuts' for the mining industry," Colorado Mining Association president Stan Dempsey Jr said.

The NMA has called on people to contact their elected representatives and urge them to oppose the budget reconciliation bill.

Its members include Barrick Gold, Sibanye-Stillwater, Cameco and Newmont.

The NRC said this month it had approved the US$25.6 billion reconciliation measure, its part of the 10-year budget reconciliation package that was now before the House of Representatives.

The NRC said its proposed hardrock mineral royalty could raise about $2 billion over 10 years and increasing the annual hardrock mining claim maintenance fee could raise nearly $800 million over 10 years.

"We're facing serious economic and environmental challenges, and today this committee addressed them with major investments across the board that will build a more sustainable economy," Grijalva said at the time.

"The health of our economy, our environment and our way of life depend on the budget decisions Congress makes over the next few weeks."

The proposal would mark one of the most substantial changes to the law that's governed US mining since 1872, Reuters reported, although it noted the full House could reverse the committee's move and the legislation faced an uncertain future in the Senate.

Grijalva had introduced the "Save Oak Flat Act" in mid-March to block the land swap sought by Rio Tinto to progress its majority-owned Resolution Copper project in Arizona.