Bluefield Daily Telegraph, Bluefield, WV

November 19, 2012

Rock Doc: Gold is precious in more ways than one


— By E. Kirsten Peters

CNHI News Service

With the price of gold well over $1,000 per troy ounce, people have asked me if they should sell Great Aunt Edna’s 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, one way or another?

And what value should we put on loyalty to Great Aunt Edna’s memory?

A geologist cannot usefully advise you about economic policy or about balancing Edna’s memory with paying the rent. But the high price of gold has led me to some rumination about the world’s 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, Nevada, where gold comes out of an open-pit mine and is processed on-site.

The final step of the work creates gold bars, called “dore.” That term means they have not yet been highly purified, so they can have some silver and other metals in them. But they’re mostly gold.

It’s tough to think clearly about gold when you’re in the presence of a lot of it, like it’s 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 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 separate dense gold particles from the lighter sand around it.

But gold is found in quite different geologic settings, too.

It’s often in veins of quartz in other rocks. (In the ancient world, Mother Nature was thought to be in some sense alive, so it wasn’t surprising the Earth would have “veins,” just as you have veins in your arms. Odd from a modern perspective, but true and preserved in our language 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. (Also odd but true, wasting my youth in such a way.)

One impressive thing about gold in your daily life is that it doesn’t dissolve at all.

The ring on your finger won’t dissolve if you throw it in the boiling pot of pasta water. The gold on your crowned tooth doesn’t dissolve despite years (or decades for some of us) 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 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 in which gold dissolves are rare – just as you know from your day-to-day living.

And that brings us back to Great Aunt Edna’s rings.

There’s no harm in taking them in and asking for a bid. But before you take the cash and walk away from the family gold, I’d recommend leaving the buy-back place and going home. One night’s sleep could help you reach a decision you won’t regret, one way or another.

There was, after all, only one Great Aunt Edna.

E. Kirsten Peters, PhD, a native of the rural Northwest, trained as a geologist at Princeton and Harvard. Her column is a service of the College of Agricultural, Human, and Natural Resource Sciences at Washington State University. She can be reached at CNHI News Service distributes her column.