nature.net
November 2006
Earthly Treasure
By Robert Anderson
Panning for gold used to be one of my long-standing desires. My own personal gold “rush” came this past year when I chaperoned my son’s school trip to Sutter’s Mill in Coloma, California. There, in 1848, James W. Marshall discovered a few gleaming yellow flecks, and in less time than it takes to holler a claim, the news was out that there was gold “in them thar hills.” Today, even novices like my son and his friends can still, with a bit of patience, wash away the worthless material in some troughs of local river sand to reveal a few flakes of the precious metal. The Marshall Gold Discovery State Historic Park has information on visiting the site.
If you’d like to learn how it’s done, go to video.google.com and type in panning gold; among the unrelated offerings, you’ll find a video of a demonstration in Alaska, the site of the state’s big gold rush of 1898.
The influence of geology on human affairs is often not appreciated, but in the quest for gold, it is manifest. The find at Sutter’s Mill triggered one of the greatest migrations in the Western Hemisphere. Go to the Virtual Museum of the City of San Francisco and click on “The Gold Rush” to learn about the boom time from those who lived it. I particularly enjoyed Sutter’s own account, “The Discovery of Gold in California,” in which he laments, “Instead of being rich, I am ruined.”
Many of the forty-niners were similarly disenchanted. Real prospecting is backbreaking work, often leaving people with little to show for it. Those foolish enough to pursue the dream might start by reading the U.S. Geological Survey’s primer on gold prospecting, which discusses different kinds of gold deposits and where they are most likely to be found.
Although jewelry consumes nearly 75 percent of the production, gold (both as coins and as jewelry) has long been the investor’s hedge against bad times. Since early 2001 its price has more than doubled, leading some to speculate that it will go much higher (go to goldprice.org for the latest prices and charts in a variety of currencies). The upward trend has also increased worries about the environmental damage associated with revved-up mining operations. A report by National Public Radio examines the controversy as it relates to one California town in the foothills of the Sierra Nevada Mountains. In part to allay environmentalists’ fears, the mining lobby has set up at least two Web sites: (www.responsiblegold.org and www.gold.org).
Given recently renewed interest in the value of this precious metal, the 2006 exhibition on gold at the American Museum of Natural History was well timed. It gave New Yorkers and visitors to the Big Apple the chance to see a room, twelve feet square by eight feet high, entirely lined in a layer of gold leaf whose total weight is only three ounces. Go to amnh.org/exhibitions/gold for more information on the exhibition, which ran from November 18 until August 19, 2007.
At the southern tip of Manhattan lies another exhibition of gold—the largest concentration of bullion in the world, stored in the Federal Reserve Bank of New York’s subterranean vault. Surprisingly, tours are available, including a glimpse of more than $100 billion in gold bars, each weighing a little more than twenty-seven pounds. Go to the Federal Reserve Bank of New York and click on “The Key to the Gold Vault” for fascinating details on the Fed’s operation.
On the West Coast, the Natural History Museum of Los Angeles County has one of the largest collections of natural gold in the world, with more than 300 pounds of gold objects. The largest nugget weighs in at 156 troy ounces, or slightly more than ten and a half pounds. The real mother lode, however, lies elsewhere.
Nearly 40 percent of all gold mined to date has come from a single geologic formation: South Africa’s Witwatersrand Basin, an ancient lake or seabed that extends 9 million acres below ground. Viewed from space, the formation is outlined by mine tailings dumped in an arc across the southern edges of Johannesburg. To follow the debate about the origins of this mammoth ore deposit, go to John L. Muntean’s article in Geotimes, the magazine of the American Geological Institute.
But there’s an even bigger gold bonanza in the Earth’s oceans. By some estimates, more than 10 million tons of gold is dissolved therein, though no one can hope to get rich quick. Many a scientist has tried to devise a scheme for extracting gold from seawater. Unfortunately, at an average concentration of ten parts per trillion, that gold isn’t worth the cost of pumping the water that carries it. Even Midas wouldn’t touch it.
Robert Anderson is a freelance science writer living in Los Angeles.
Copyright © Natural History Magazine, Inc., 2006