Giant mining equipment has stripped away the palm trees and other vegetation from a jungle bluff here with a Malay name that translates to “Iron Hill.” Huge power shovels gouge long furrows down cliffs of fuchsia clay, scooping out the shiny black iron ore at their base.

The mine here operates round the clock, seven days a week. The Chinese-controlled CAA Resources, which reopened the dormant mine early this year, has rapidly ramped up production to an annual rate of 500,000 tons, with plans to double it by next year.

Its ambitions, though, are being undermined by the shifting global terrain: Iron ore sells for less and less these days.

“China still needs a lot of steel for infrastructure, housing projects and rails,” Li Yang, CAA’s chairman and chief executive, yelled as ore-processing machinery clanked noisily nearby. “The only problem is the pricing.”

With seemingly insatiable demand from China, the price of iron ore, along with many other commodities, soared for most of the past decade. China manufactures half the world’s steel, which is made from iron and used for housing construction, rail lines, carmaking and more.

The boom helped support the rapid growth of companies like CAA, as well as the economies of developing countries rich with resources. From Indonesia and Australia to Peru and Brazil, multinationals and Chinese companies embarked on large-scale, long-term investments in mines.

But the dynamics have changed — and the current downturn may reflect a new reality. China’s economy, once growing in the double digits, has slowed to around 7 percent, with industrial output dropping even more dramatically. Many commodity companies, though, have ramped up production to meet that earlier pace of demand.

The result is a double blow to natural resources companies and emerging markets, with few sectors hurt more than iron ore. Prices are down 48 percent since the start of the year, to $70 a metric ton, a five-year low.

Even in the face of falling prices, producers show no signs of easing off, with low-cost industry giants leading the charge.

Vale of Brazil said in August that it wants to double shipments to China in five years. BHP Billiton of Australia announced plans the same month to invest $2 billion in mine expansion projects. Rio Tinto, a company based in London with extensive operations in Australia, is in the process of bolstering production 13 percent by next year and another 8 percent by 2017.

Chinese companies, too, have been relentlessly expanding overseas. In Malaysia, the number of iron ore mines in operation has increased more than sevenfold since 2007, mainly from Chinese investment.