Aluminum Was a Precious Metal

Bas-relief aluminum door in the Hunt Library.
Bas-relief aluminum door in the Hunt Library.

Various materials and artifacts bring a high price. This is because of their beauty, low availability, or craftsmanship. Some objects are so costly they are precious. These include platinum, silver, and gold. But not aluminum. Yet during the 19th Century the metal was treasured.

Aluminum Deposits

It is the most common metal in earth. It is not especially beautiful. So why did the metal once bring so high a price? In a sense it was scarce. It was unavailable.

Availability

Diamonds are highly prized. Yet, they are fairly common. The number of diamonds released to the public each year is small. The number is carefully monitored. If a lot of diamonds were released, their price would take a nosedive.

Aluminum is reactive. It does not exist in nature as the metal. No one in the 19th Century knew how to produce it from ore. The methods employed to obtain other metals did not work. For this reason, it was extremely difficult to obtain the metal.

It was not until 1854 that the shiny metal was anything less than precious. And it wasn’t until after the 1880s that it became a useful raw material. Until then, it was just as likely as not to be used as jewelry.

The Trick

The trick is the metal can not be isolated by simply heating with a reducing agent. Neither is it prepared by electrolysis from water solution. The answer lay in electrolyzing a mixture of molten cryolite (Na₃AlF₆) and calcium fluoride (CaF₂). Liquid metal sinks and is drawn off.

This Hall-Héroult Process led to the demise of precious aluminum. In fact, prices decreased sharply. It is so cheap it is used to can soda and beer.

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