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Pick the Ore Mineral of the Year! Voting for Copper vs Molybdenite will remain open for 48 hours. Credit: David M. Maietta and Harold Moritz

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Over the past century and a half the discovery of thousands of copper artifacts, primarily on Wisconsin soil, has given rise to speculation and interpretation of their manufacture and function. Many o...

Pick the Ore Mineral of the Year! Voting for Copper vs Molybdenite will remain open for 48 hours. Credit: David M. Maietta and Harold Moritz

United States Senate Committee on Appropriations

It’s down to the final match to select our Ore Mineral of the Year! Native copper is the purest form of copper ore with a deep history with humans, while slippery Molybdenite confounded us for centuries until finals sharing its secrets on how to enhance all it touches. Both are worthy contenders, but only one can win! Native copper forms reddish-brown branching tendrils that are valued for their beauty and utility. The coppery sheen tarnishes to a green or black patina of malachite, azurite, cuprite, and other minerals. It is metallic, highly malleable and ductile, with unusually high electrical and thermal conductivity. Native copper has the highest concentration of copper of any copper ore, with only trace contamination by other elements. But native copper deposits are typically too rare and too small to be primary mining targets. Instead, some of the more than 150 copper-containing minerals, primary chalcopyrite, chalcocite, and bornite, are mined to produce 20 million tons of copper per year. Native copper has a long history with humans as one of our first ores. Its ductility and malleability allowed prehistoric cultures to cold-shape copper, and its low melting temperature allowed ancient peoples to develop metallurgy around campfires. The demand for copper is increasing, with the metal essential to everything from simple wires to cutting-edge technological advancements. Copper deposits are being depleted at a faster rate than any other ore, even though iron and aluminum are mined in higher volumes. You can learn more about copper in its Round 1 writeup the fan highlights, and in its semifinal writeup and fan highlights. Molybdenite forms greasy, soft silver hexagonal flakes. It’s the primary ore of molybdenum and the only ore of its trace contaminate rhenium. While this molybdenum ore looks and feels similar to graphite, it is denser, has a more blue tint in its streak when rubbed on paper, and is shinier. It was also mistaken for a lead ore until the element molybdenum was discovered in 1778 and isolated in 1781. It took until the early 1900s to identify its most common trace contaminate and mining byproduct rhenium. Molybdenite forms in high-temperature hydrothermal deposits, with the richest ore deposits usually mined in conjunction with massive copper deposits. About 200,000 to 250,000 tons of molybdenum is produced globally each year, decreasing in recent years as no new mines have started up. The largest producers of molybdenum are China, Chile, Peru, and the United States. While molybdenum has been found in a Japanese sword from 1330, it took until the early 1900s to reliably process the ore and use it commercially. Most molybdenum is added to steel alloys to impart strength and increase heat and corrosion resistance, but it’s also a high-performance lubricant. Molybdenum powder is also a fertilizer additive to increase nitrogen fixation, and as an anti-corrosion paint additive. Rhenium is used in metal alloys in wind turbines and automobile catalysts. You can learn more about molybdenite in its Round 1 writeup the fan highlights, and in its semifinal writeup and fan highlights. **Please vote only once per player.** Multiple players may vote using the same device. **Voting for each match starts and ends at 00:00 GMT.** Due to site limitations, the polls will continue to be visible, but only votes cast in the 48-hour period will be tallied. time remaining