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November-December 2011

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Connoisseur'S Choice: Alabandite Uchucchacua Mine, Oyon Province Lima Department, Peru

The Swedish chemist Carl Wilhelm Scheele (1742–86) has to be considered one of the preeminent scientists of his time. Scheele was on the forefront of chemical research doing experiments that led to the discovery of oxygen, molybdenum, tungsten, barium, and hydrogen; unfortunately, he is not credited with the discoveries. In the case of oxygen, he made the discovery three years before Joseph Priestly and Antoine Lavoisier, but he published his results after Priestly did. Scheele, working with the mineral pyrolusite, became the first to isolate a pungent, eye-watering gas that we know today as chlorine. Also, during his experiments with pyrolusite, he isolated a compound that he felt sure contained a new element, which eventually was named manganese (Strathern 2001; Stwertka 2002). Manganese is an important additive to steel, and manganese dioxide is a component of dry-cell batteries. Mineral collectors are most familiar with manganese oxides, such as manganite and pyrolusite; the carbonate rhodochrosite; and the silicate rhodonite, but manganese sulfides are decidedly rare. Of these, two may be familiar to collectors—one is hauerite from Sicily, which occurs in exceptional octahedral crystals. The second does not normally occur in exceptional crystals and until recently has usually not been represented in most mineral collections, and that is the mineral alabandite. 

Paul W. Pohwat is the collections manager (minerals) in the Department of Mineral Sciences at the National Museum of Natural History.

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