The world's major miners are not discovering enough gold deposits to make up for all the extraction they have engaged in over the past decade and a half, a fact that suggests the scarcity of the precious yellow metal could grow in coming decades.

That's according to a new report by Canada-based Metals Economics Group, which found the estimated 289.8 million ounces added to the on-the-ground reserves of the world's 26 largest miners through new discoveries an acquisitions from 1997 to 2011 would not have been enough to keep up with their extraction volume for the same period, which averaged somewhat under 2 million ounces per producer per year.

And those numbers don't even tell the entire picture, since wider industry data suggests most of the discoveries over that period were added through brownfields work and exploration at older, known deposits.

Gold

Gold in Reserves, Resources, and Past Production in Major Gold Discoveries by Country, 1997-2011

Despite the apparent shortfall in new discoveries, the biggest reserves replacement challenge faced by the major producers and the industry as a whole is not that there is no gold left, but that all the easy gold has been found. Worldwide, the total gold in reserves and resources at development-stage projects is essentially equal to that in currently producing mines, the mining industry research and analysis group said in a statement.

However, with increasing risk of political, regulatory, and tax instability in many resource-rich nations, declining grades, rising costs, and dramatically longer development times, the amount of gold available for production in the near term is likely far less than has been found.

These companies held sufficient reserves for 21 years of production at their 2011 rate. However, increasing production exacerbates the need to replace reserves, a summary of the report stated.