Robert Jameson the scottish naturalist and mineralogist gave the name of bournonite in 1805 after the french crystallographer and mineralogist Jacques Louis de Bournon who had determinated the chemical formula of this mineral. It is an interesting fact, before that, for a short period from 1797 endellionite was the name of the mineral, because it had been known from a mine near St. Endellion (Cornwall, England) already. The bournonite is an important ore mineral consisting lead, copper and antimony. It issues on moderate temperature in hydrothermal veins, mostly together with galena, tetrahedrite, sphalerite, quartz, siderite, stibnite, baryte etc. It can be found in massive, grainy, columnar aggregations, but the tabular, toothed crystals are also common which can often look like twinned gears, their other name is ’cogwheels’. Localities: Romania, Czech Republic, Austria, Germany, England, Peru, Bolivia, etc.