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M) Cockade texture quartz; N) Moss texture silica; O) Comb texture quartz; P) Pseudo-

acicular quartz; Q) Lattice-bladed calcite replaced by quartz; R) Ghost-sphere texture quartz. (XP = view under crossed polars).

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Figure 8. Examples of textures observed in samples from the Veta Madre at Guanajuato. Jigsaw texture quartz observed in plain light (A) and under crossed polars (B). Plumose texture silica in plain light (C) and under crossed polars (D). Lattice bladed calcite plain light (E) and under crossed polars (F). Lattice bladed calcite replaced by quartz in plain light (G) and under crossed polars (H). Acicular calcite replaced by quartz in plain light (I). Colloform texture silica under crossed polars (J). 44

Figure 9. Relative abundance of the different mineral textures and fluid inclusion characteristics in samples from the Veta Madre, Guanajuato, Mexico.

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Figure 10. Relationship between the average Au grade of samples and the presence or absence of each mineral texture and evidence of boiling fluid inclusions in samples from

the Veta Madre, Guanajuato, Mexico.

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Figure 11. Relationship between the average Ag grade of samples and the presence or absence of each mineral texture and evidence of boiling fluid inclusions in samples from

the Veta Madre, Guanajuato, Mexico.

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Figure 12. Distribution of Au (right) and Ag (left) grades (in log ppm) plotted as a function of whether a particular mineralogical or fluid inclusion feature was present or absent. Also shown by the vertical line on each histogram is the mean metal grade for samples in which the feature is present (blue) or absent (red). A t-test was applied to each pair of data to assess whether the mean values were statistically different and the results are shown as the probability (i.e., P<0.05 indicates that there is less than a 5% chance that the difference is due to chance). JTS = jigsaw texture silica; CTS = colloform texture silica; PTS = plumose texture silica; LBC = lattice-bladed calcite; FI = fluid inclusions;

MQ = massive quartz.

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Figure 13. The flow stream for the binary classifier within the statistical software package SPSS Clementine applied during the development and testing of statistical models for Au

(top) and Ag (bottom) from Guanajuato, Mexico.

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Figure 14. Log-normal distribution of Au (top) and Ag (bottom) grades in samples from

Guanajuato, Mexico.

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Figure 15. Relative importance of variables used to build models to predict Au (top) and

Ag (bottom) concentrations at Guanajuato, Mexico.

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Figure 16. Boiling intensity factor (A) and Au (B) and Ag (C) grades of samples collected along a traverse perpendicular to the Veta Madre, and boiling intensity factor for samples from an angled drill core from the surface to the Veta Madre. JTS = jigsaw

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