China's economic slowdown is putting the kibosh on the 10-year rally in commodities prices, says Daniel Yergin, vice chairman of research and consulting firm IHS.

The IHS non-oil commodity index has dropped 27 percent since 2008.

"Over the past decade, commodity exporters have been the great beneficiaries of the commodity 'supercycle' — the combination of accelerating demand and rising commodity prices that have delivered GDP [gross domestic product] growth," Yergin writes in The Wall Street Journal.

Editor’s Note: Forbes Columnist: ‘Who the Hell Cleared This?’ (See Shocking Video)

"With China's slowing, the supercycle is over, meaning tough choices ahead."

China maintained an economic growth pace of 10 percent for 30 years, Yergin notes. "At some point such growth was bound to become unsustainable, and that is what is now happening."

The nation's GDP has expanded less than 8 percent for the last five quarters — 7.5 percent in the second quarter.

For countries dependent on commodity exports, "the China Chill is a cold wind indeed," Yergin professes. "China will still be the biggest market for industrial commodities — but without the same accelerating growth in demand."

That's not good news for the economies of the exporters. They can "no longer bank on the bounty of raw-material earnings to maintain economic growth and fund government spending," Yergin writes.

The most widely held commodity is probably gold, and it has dropped more than 20 percent so far this year, trading at $1,341.20 midday Monday.

Gold analysts are the most bearish they've been in seven weeks, according to a Bloomberg report, as they await a tapering of the Federal Reserve's quantitative easing that may come as soon as next month.

Of 30 analysts Bloomberg surveyed, 14 expect gold prices to fall this week, nine expect an increase and seven are neutral.

Editor’s Note: Forbes Columnist: ‘Who the Hell Cleared This?’ (See Shocking Video)