Neglected Members of the Precious Metals Family

Ever wonder how gold, silver and the other precious metals become so “precious” in the first place? Perhaps you already know that their chemical makeup, rarity and investment value have a lot to do with it.

What you may not know, though, is that there are several other children in the precious metals family that don’t have quite the notoriety as their gold, silver and platinum siblings. You might consider them the “middle children” of the precious metals family since they tend to get overlooked.

But just because these little known metals sound like something out of a science fiction novel doesn’t mean they aren’t also valuable or any less rare. In fact, as you’ll learn below, three of these metals are even more scarce (and more strange) than almost any other substance on Earth—including gold.

(Rh) Rhodium

Rhodium, a so-called noble metal, is one of the rarest and most valuable of all the precious metals.  It is nearly identical to platinum, and is extremely resistant to corrosion and melting. The price of rhodium has experienced shocking fluctuations in the last 20 years—enough to make gold and silver look boring.

For instance, until 1985, rhodium never traded above $1000, but it rose to $5350 in 1991, sunk to $183 6 years later, then spiked back up over $10,000 in mid-2008. Analysts typically link this behavior to the use of the metal in the auto industry, as well as mining strikes in South Africa, the world’s chief rhodium supplier.

Major producers: South Africa, Russia and Canada

Uses: It is primarily used as one of the catalysts in three-way catalytic converters in automobiles. Rhodium is also applied as aplating for sterling silver for tarnish resistance and used in many nuclear reactors.

(Ir) Iridium

Iridium is undoubtedly one of the most strange and extreme metals not only on this list, but also on the planet. Only one other substance on Earth matches it in terms of density. Iridium is twice as dense as lead and 8 times that of granite. (A 6 inch cube made of iridium would weigh as much as an average adult human!) Also, according to scientists’ best educated guesses, iridium is the clear winner for rarity—about twelve times rarer than gold.

Major producers: South Africa

Uses: Don’t hold your breath for iridium jewelry anytime soon. Because of its high melting point, working with iridium is more trouble than it’s worth. However, due to its corrosive resistance, small quantities of iridium in powder-form can be found all over the place, from compasses and watches to spark plugs and cancer treatments.

(Re) Rhenium

Named after the river Rhine in Europe, rhenium was the last stable element to be discovered. Its claim to fame is being considered the hardest metal and boasting the highest melting point (3186°C or 5767°F).

Major producers: Chile, Kazakhstan and the United States

Uses: Nickel-based alloys that contain rhenium are used in the combustion chambers, turbine blades, and exhaust nozzles of jet engines. The rare metal also holds strategic importance for the military because of its use in high-grade military jet and rocket engines.

Other obscure, yet fascinating, members of the precious metal family include:

• Osmium – densest metal on the planet
• Indium – heavily used in WWII as a coating for bearings in aircraft engines
• Ruthenium – just 12 tons are mined each year (compared to the estimated 2,500 tons of gold that is mined annually)

What is your favorite precious metal and why?

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