394 molybdenite, chalcocite, bornite, etc.) do not exceed 2 or 3 % of the total rock, while gangue minerals are above 96 %. Even more critical is the case of high sulfidation epithermal gold deposits (such as Yanacocha and Pierina in Perú; or La Coipa and Can-Can in Chile); where gold ore is usually below 1gr/ton (1 ppm), which in percentage means only: 0.0001% of the rock; it means that 99.9999 % is gangue, composed by different types of quartz, eventually accompanied by scarce alunite, clays, pyrophyllite, jarosite, Fe-hydroxides, etc. Therefore, it is easy to deduce that any kind of problem, such as high cyanide or lime consumption, unusual resistance to crushing, or reduced recovery percentage, are mainly caused by gangue minerals. Of course, we cannot ignore the case where sulfides, sulfosalts or the same native sulfur, are also cyanide consumers; but even in these cases, we are speaking of gangues. Although it is obvious and clear that gangue minerals are the main component in lowgrade deposits, the same is true for practically all types of deposits, even those with higher grades, since the proportion of ore is usually lower than that of gangue. 3. GEO-METALLURGICAL CHARACTERIZATION (GMC) To implement a Geometallurgical Model it is necessary to perform a global GeoMetallurgical Characterization procedure. Nothing more related and committed to the TRC than the Geo-Metallurgical Characterization, which is called “global” because includes the following four analysis (Figure 1): 3.1. Chemical characterization Apart from traditional assays of both, economic and deleterious elements, should be included from exploration phase: Au and Ag cyanide analysis (CN_Au and CN_Ag); as well as “Sequential Cu analysis”: Total Cu analysis (TCu), acid-soluble Cu (AcSCu), cyanide-soluble Cu (CNSCu) and refractory Cu (RCu). 3.2. Mineralogical characterization "Bulk" mineralogical analysis by X-Ray Diffraction (XRD) is the most used technique in geometallurgical characterization; however, it is expensive and time consuming. Of course, alternative methods such as optical microscopy, QEMSCAN (Quantitative Evaluation of minerals by Scanning Electron Microscopy) and TESCAN are more expensive (Table 1). On the contrary, FTNIR analysis (Fourier Transform Near Infra-Red) is the more suitable because it is faster and cheaper (Canchaya 2016). FTNIR analysis is explained in Figure 2.
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