Issue link: https://read.dmtmag.com/i/109821
Resource Mapping ���Figure 3. A map shows old mine workings for the La Cadena Area of the central Zacualpan District. Readily apparent from Figure 3 is a pronounced northwesterly and northerly alignment of these old mine workings. Geological studies confirm these directions as being the principle orientations for the silvergold veins as shown in Figure 4, which is a compilation of all the individual vein orientations as measured by IMPACT���s geological team in the field. Also important is the size and/or type of the old mine workings, as the larger ones represented places of past production mining. The smaller workings (mostly small prospecting pits dug in the ground) likely represented places where quartz veins are present, but didn���t have appreciable silver or gold content. Most of these newly re-discovered old mine workings are in excess of 100 years old, with many dating back to the Spanish Colonial times (prior to 1811). For the older mine workings, the work was largely carried out by hand, with the ore-bearing rock carried by humans or mules to processing plants, often many kilometers away. Consequently, these ore-bearing rocks needed to be sufficiently rich (generally greater than 1,000 grams of silver per tonne of rock) to justify these efforts. Now with the advent of mechanized mining, trucks for transport and the relatively high price of silver (currently valued at $30 per ounce or $1 per gram), silver grades of 100 grams per tonne, given a sufficient quantity, now are economically feasible for mining. IMPACT Silver���s new mines all are basically expansions of historical mines. Adding Modern Techniques ���Figure 4. A map compiles vein-orientation measurements from rock outcrops for the La Cadena Area. ���Figure 5. A color-contoured plot of silver values in soil samples for the La Cadena Area uses the inverse distance squared method. 16 G E O W O R L D / F E B R U A R Y 2 O 1 3 Another important source of information is the soilsampling surveys recently conducted by IMPACT Silver in which small quantities of soil are collected at 25meter intervals and then analyzed for 30 elements, including silver and gold. Figure 5 shows the geochemical values for silver contoured by the ���inverse distance ���Figure 6. A Vein Interpretation Map shows the interpreted veins and faults for the La Cadena Area based on data from Figures 3, 4 and 5.