Tantalum is a soft metal that has high electrical conductivity and an extremely high melting temperature. It is used in a variety of electronic devices in everything from cars to personal computers, primarily in the form of tantalum-based capacitors — components of circuits that store energy between opposing metal plates.
Tantalum can also be combined with carbon to form a hard tantalum carbide, which has applications as tooling for metalworking equipment and as a component in jet engines. A 1/4″ diameter rod of 99.9% Ta with a mass of 125 grams costs around $700.
In 2018, $8.6 billion worth of gold was extracted from mines in the United States, equal to roughly one-third of the total value of metals extracted from U.S. mines that year. Somewhat surprisingly, jewelry accounts for only about 46% of gold processed in the United States, with electronics applications another 40%, and coins making up most of the rest. A chunk of 6.4 grams (0.22 ounces) of nearly-pure gold can be purchased for a little over $1,000, or approximately $150 per gram.
Strontium occurs in mineral deposits throughout the United States, though it hasn’t been mined here since the 1950s. The United States imported nearly 28,000 metric tons of strontium in 2018, primarily from Mexico and Germany. Strontium has applications spanning many industries, from an additive in drilling fluids to pyrotechnics. When combined with titanium and oxygen, strontium titanate has interesting and useful properties in various electronic or magnetic applications.
The mineral strontium is extracted from celestite, which costs about $75 per ton. However, 25 grams of ultra-pure strontium cost over $2,000.
9. Silicon carbide
Silicon carbide, which is a material made of silicon and carbon, can have a variety of different crystal structures, with each structure having its own unique properties. Although the materials that make it up (namely, silicon and carbon) are relatively inexpensive, the costs of making certain kinds of crystalline SiC increases the price significantly. For electronics-grade material, a small salad plate sized-wafer of SiC can cost over $1,000.
Silicon carbide is extremely hard, and one of the structures it can adopt has nearly the same hardness and optical properties as diamonds. In another structure, it has uses in electronic materials and forms the backbone of many consumer LED light bulbs.
10. Platinum-group metals
The platinum-group metals include platinum, palladium, iridium, osmium, rhodium, and ruthenium. These very rare metals are often grouped because they are typically found together in nature, and because they share similar properties. Palladium is used in catalytic converters in cars, and osmium is used in fountain-tip pens and electrical contacts.
Other uses for platinum-group metals include catalysts for industrial processes, medical devices, electronic applications, jewelry, and laboratory equipment. Prices of the materials vary but are usually quite expensive. For example, 6.5 grams (about 0.23 of an ounce) of platinum can cost about $1,000.
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