Special Report

The Most Expensive Materials on Earth

1. Diamond

Carbon forms the basis for all organic materials and is abundant on Earth. However, its value varies a great deal depending on its purity, composition, and atomic structure. For instance, a bag of charcoal (graphitic carbon) is relatively inexpensive. Charcoal — the kind used in grilling — costs less than a cent per gram (about 0.04 ounces).

The price of high purity diamond, on the other hand, is orders of magnitude higher, thanks in part to diamonds’ value in the retail jewelry market. For instance, research-grade diamond powder, with diamond particles 1 micrometer in diameter — about 1/20th the size of a human hair — costs about $120 per gram. Increasing the size of a single crystal of diamond to 1 g, or 5 carats, would dramatically increase the price, to well above $10,000.

2. High-purity aluminum

Aluminum has extremely high electrical and thermal conductivity, meaning it conducts heat and electricity very well, making it great for certain electronics applications.

Most commercially-available aluminum is quite inexpensive given that it is one of the most abundant materials on the planet, constituting 8% of the Earth’s crust. A roll of aluminum foil costs a few dollars at the supermarket. However, when extremely pure aluminum is needed, for example for certain research studies, the manufacturing cost increases the prices significantly. A 4″ x 4″ piece of ultra-pure aluminum foil can cost a few hundred dollars.

3. Electronics-grade silicon

This material is also extremely abundant, and most commercially available silicon is generally inexpensive. Silicon comprises about 25% of the Earth’s crust, making it relatively easy to find and mine.

Silicon is an essential component of most electronic devices — computer chips and solar panels are primarily made from silicon. Electronics-grade silicon, however, requires a certain purity and crystallinity (the way in which the atoms in the material are arranged), which add considerable engineering costs to the raw materials. Once a silicon wafer with the diameter of a large dinner plate and thickness of less than 1mm (about 1/32nd of an inch) has been fully processed into an array of state-of-the-art computer chips, it can be worth more than $10,000.

4. Silver

In the United States, $440 million worth of silver was extracted from mines, totaling about 900 tons. Most silver is used in electronics, jewelry, or for photographic equipment. For example, 20 grams (about 0.7 of an ounce) of ultra-pure silver used for research purposes costs about $250.

Silver serves a variety of applications owing to its unique properties. It is the most electrically conductive of any element, even beating out copper. However, the high cost makes it economically unfeasible to wire our cities and houses. Silver can also be found in some optical coatings (such as high-end mirrors), silver-oxide batteries, soldering, and more.

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5. Rhenium

Rhenium is a metal with extraordinary properties. It is one of the rarest materials on Earth, and it has the third highest melting temperature of all known materials. As such, it is a critical component in alloys used in jet engines and in some temperature sensors given its ability to withstand high temperatures.

Rhenium exists in Earth’s crust in tiny quantities. In other words, we have to extract approximately 1 billion times more material from the Earth than we get in rhenium, once refined. Just 5 grams (about 1/6th of an ounce) of 99.995% Rhenium powder costs almost $400.