But now comes word that it isn’t just wildlife that can go extinct. The element gallium is in very short supply and the world may well run out of it in just a few years. Indium is threatened too, says Armin Reller, a materials chemist at Germany’s University of Augsburg. He estimates that our planet’s stock of indium will last no more than another decade. All the hafnium will be gone by 2017 also, and another twenty years will see the extinction of zinc. Even copper is an endangered item, since worldwide demand for it is likely to exceed available supplies by the end of the present century.

Gallium’s atomic number is 31. It’s a blue-white metal first discovered in 1831, and has certain unusual properties, like a very low melting point and an unwillingness to oxidize, that make it useful as a coating for optical mirrors, a liquid seal in strongly heated apparatus, and a substitute for mercury in ultraviolet lamps. It’s also quite important in making the liquid-crystal displays used in flat-screen television sets and computer monitors.

As it happens, we are building a lot of flat-screen TV sets and computer monitors these days. Gallium is thought to make up 0.0015 percent of the Earth’s crust and there are no concentrated supplies of it. We get it by extracting it from zinc or aluminum ore or by smelting the dust of furnace flues. Dr. Reller says that by 2017 or so there’ll be none left to use. Indium, another endangered element—number 49 in the periodic table—is similar to gallium in many ways, has many of the same uses (plus some others—it’s a gasoline additive, for example, and a component of the control rods used in nuclear reactors) and is being consumed much faster than we are finding it. Dr. Reller gives it about another decade. Hafnium, element 72, is in only slightly better shape. There aren’t any hafnium mines around; it lurks hidden in minute quantities in minerals that contain zirconium, from which it is extracted by a complicated process that would take me three or four pages to explain. We use a lot of it in computer chips and, like indium, in the control rods of nuclear reactors, but the problem is that we don’t have a lot of it. Dr. Reller thinks it’ll be gone somewhere around 2017. Even zinc, commonplace old zinc that is alloyed with copper to make brass, and which the United States used for ordinary one-cent coins when copper was in short supply in World War II, has a Reller extinction date of 2037. (How does a novel called The Death of Brass grab you?)

Zinc was never rare. We mine millions of tons a year of it. But the supply is finite and the demand is infinite, and that’s bad news. Even copper, as I noted above, is deemed to be at risk. We humans move to and fro upon the earth, gobbling up everything in sight, and some things aren’t replaceable.

So the penny will stick around. The real question is how to make it affordable. Sharply rising world prices in recent years for its components, zinc and copper, have made it a money loser. The same holds for the five-cent coin, made of copper and nickel.

In the last federal fiscal year, it cost the Mint 1.67 cents to make each of the roughly eight billion pennies it churned out. In other words, taxpayers paid more than $130 million for coins valued at only $80 million. Looked at another way, even your opinions have become more expensive. It costs about 3 cents to put in your 2 cents.

The finances of the nickel are even grimmer. Each 5-cent piece cost 9.5 cents to make last year. So more than $120 million was spent to produce about $65 million worth of that coin.

[...]

These losses cannot be sustained, says Edmund C. Moy, the Mint’s director. “You can’t lose money on two of our big products and hope to have a long-term viable organization,” he said.

Mr. Moy wants Congress to give his agency more flexibility to “determine the metal content of the coins at any given time,” depending on shifting world prices, which have declined somewhat of late. One idea being considered is a copper-coated penny with a core of steel instead of zinc, as is now the case.

As it happens, we are building a lot of flat-screen TV sets and computer monitors these days. Gallium is thought to make up 0.0015 percent of the Earth’s crust and there are no concentrated supplies of it. We get it by extracting it from zinc or aluminum ore or by smelting the dust of furnace flues. Dr. Reller says that by 2017 or so there’ll be none left to use.

The world currently has around ten years worth of copper reserves.

The world has had about ten years worth of copper reserves for the past century.

When proven reserves decline much below ten years, the price goes up. When the price goes up, old mines re-open, prospecting increases and the reserves go up. when the reserves get much past ten years, the prices goes down...