MINERÍA la mejor puerta de acceso al sector minero MINERÍA / SEPTIEMBRE 2023 / EDICIÓN 552 164 ta, un sulfuro de hierro, que la denominan «oro de los tontos»; la chalcopirita, un sulfuro de cobre y hierro, y algunas micas que logran su confusión. El color amarillo de oro podría variar, el cual dependerá del porcentaje de plata que pudiera contener, a mayor cantidad de plata, mayor será su palidez. La maleabilidad y la ductibilidad podrían alterar al oro, si contiene impurezas como el plomo en 0.005%, teluro en 0.01% o bismuto un 0.1%, que lo vuelven frágil. El oro posee una dureza, que es la capacidad que ofrece su superficie a ser rayada, de 2.5 a 3 en la escala de Mohs, es un metal blando, más que la plata, pero más duro que el estaño. Esta dureza puede aumentar con algunas impurezas metálicas. Su peso específico o relación entre su peso y el de un volumen igual de agua a 4 ºC, es 19.3 g/cm³; puede disminuir con la presencia de plata, cobre y otros metales. Cristaliza en el sistema cúbico, formando octaedros y dodecaedros, con frecuencia distorsionados en crecimientos dendríticos y en hojas, cristales cúbicos son escasos. Los mineros prehispánicos habrían podido obtener oro nativo o puro, con cierta dificultad, de los llamados «filones de oro» y fácilmente de los «placeres auríferos». Gold has a hardness, which is the capacity of its surface to be scratched, of 2.5 to 3 on the Mohs Scale. It is a soft metal, softer than silver but harder than tin; this hardness can increase with some metallic impurities. Its specific gravity, or ratio between its weight and that of an equal volume of water at 4 °C, is 19.3 g/ cm³; it may decrease with the presence of silver, copper and other metals. It crystallizes in the cubic system, forming octahedrons and dodecahedrons, often distorted in dendritic growths and in sheets. Cubic crystals are scarce. Pre-Hispanic miners would have been able to obtain native or pure gold, with some difficulty, from the so-called "gold veins" and easily from the "auriferous placers". "Gold veins" are mineralized vertical structures such as cracks, fissures, openings, etc. that have occurred in the earth's crust and were filled with gold. These structures are formed by rising hydrothermal solutions, mainly of quartz and gold; these structures can have thicknesses of up to a few meters. These auriferous structures, which can also be inclined, as well as horizontal or in other arrangements, are found in the interior of the earth's crust. These "gold veins" that had surfaced were broken using bars, chisels, wedges and hammers; the pieces obtained were taken to the milling sites, and the material was washed in pans, where pure gold was recovered. They tried to extract only the most valuable part, perhaps an ounce of gold per ton, wherever possible, following the course of the mineralized structure. Gold was more easily obtained from the so-called "auriferous placers" or also "auriferous panning places", which are the result of the erosion of the "gold veins" by rain, ice, snow and wind; they can be located in areas of undulating topography. The process of transporting the eroded product, due to the high specific weight of gold, allows it Oro. / Gold.
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