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Rock doc: The right time to sell

By September 10, 2010

Special to the Democrat

With the price of gold over $1,000 per troy ounce, people have asked me if they should sell Great Aunt EdnaÕs rings and bracelets. Is the price of gold going to go up more based on fears of economic troubles? Will governments around the world take actions that change the price a lot, one way or another? And whatÕs the value we should put on loyalty to Great Aunt EdnaÕs memory?

A geologist cannot usefully advise you about economic policy made at the international level or about balancing EdnaÕs memory versus being able to pay the rent. But the high price of gold has led me to some rumination about the worldÕs first, extraordinarily precious metal.

Not all that glitters is gold, to be sure, but when I once had the chance to personally heft a gold bar (no easy feat for a lightweight), I surely admitted that gold has a strong allure. I was visiting a geologist at Round Mountain, Nev., where the gold comes out of an open-pit mine and is processed on-site. The final step of the work creates the gold bars, which are called Òdore.Ó That term means they have not yet been highly purified, so they can have some silver and other metals in them. But theyÕre mostly gold.

ItÕs tough to think clearly about gold when youÕre in the presence of a lot of it, like itÕs tough to be completely unemotional in the presence of the Hope Diamond. But here, in the safety of print and away from stacks of gold bars, let me lay out a bit of what I know about gold.

People likely learned to mine gold long ago where it occurred in the richest stream and beach deposits. If gold grade is high enough, you can literally simply look down at your feet as you walk along a sandy beach and pick out small nuggets and grains of gold. When gold grade drops below that, individual prospectors can either pan for gold or send their sandy diggings down sluices to process it. Both approaches help separate dense gold particles from the lighter sand around it.

But gold is found in quite different geologic settings, too. ItÕs often in veins of quartz in other rocks. (In the ancient world, Mother Nature was thought to be in some sense alive, so it wasnÕt surprising the Earth would have Òveins,Ó just as you have veins in your arms. Odd, from a modern perspective, but true, and preserved in our language down through the millennia.)

Geological veins are made by fluids, circulating in the Earth and depositing minerals that get left behind. I spent several years in graduate school studying how much gold will dissolve in fluids in the Earth. (Odd, also, but true, wasting my youth in such a way.)

One impressive thing about gold in your daily life is that it doesnÕt dissolve at all. The ring on your finger wonÕt dissolve if you throw it in the boiling pot of pasta water. The gold on your crowned tooth doesnÕt dissolve despite years (or for some of us, decades) of being immersed in spit, hot coffee and all the rest.

So the question for my studies as a student, essentially, was what conditions and chemicals in the Earth made it possible for gold to dissolve into fluids and move, then drop out of solution and into the veins from which we can mine it today. The answer had to do with sulfur and oxygen and some difficult points of chemistry, with lots of calculations thrown in to add to the labor. But the main issue was that the conditions where gold dissolves are rare, indeed Ñ just as you know from your day-to-day living.

And that brings us back to Great Aunt EdnaÕs rings. ThereÕs no harm in taking them in and asking for a bid. But before you take the cash and walk away from the family gold, IÕd recommend leaving the buy-back place and going home. One nightÕs sleep could help you reach a decision you wonÕt regret, one way or another. There was, after all, only one Great Aunt Edna.

Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. This column is a service of the College of Agricultural, Human, and Natural Resource Sciences at Washington State University. Dr. Peters can be reached at [email protected]

E. Kirsten Peters

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