The Guanajuato property overlies the core of the prolific Veta Madre silver-gold structure. These world-class low sulfidation epithermal deposits to date have total production of over one billion ounces silver and 4 million ounces gold over a 450 year mining history. One marvellous aspect of world class deposits is their defiance of typical size due to multiple phase, overlapping events. This is borne out by structural studies and fluid inclusion work. The fluid inclusion work has shown that boiling horizons (and associate silver-gold deposition) occur over a vertical range of at least 600 metres below the present surface. There are consistent structural aspects between the various deposits on the Guanajuato property, which include bends, step-over and cymoid loops.
To a certain degree deep extensions of mineralization can be found by following known deposits down plunge to depth. Drill hole EUG10-057 has shown that systematic drilling can discover new "blind" mineralized zones. Many zones at Guanajuato are relatively small, but as history has shown, conditions are primed for world-class low sulfidation epithermal silver-gold systems. Since the bottom of the silver-gold mineralization has not been reached the Company is optimistic that with diligent, systematic work any deep large silver-gold deposit will be found with the 2010-2012 deep drilling.
When Great Panther acquired the Guanajuato Mines in 2005, there were no NI43-101 compliant resources and the Company had to rehabilitate the mine in order to begin establishing a new resource base at depth.
When Great Panther acquired the Guanajuato Mines in 2005, there were no NI43-101 compliant resources and the Company had to rehabilitate the mine in order to begin establishing a new resource base at depth. Since then, four NI 43-101 have been completed.
The 2012 Guanajuato Mine mineral resource estimate contains Measured and Indicated mineral resources of 5,649,000 Ag eq oz including 3,530,000 Ag eq oz in the Measured category and 2,119,000 Ag eq oz in the Indicated category (see tables below). Inferred mineral resources are estimated at 2,503,000 Ag eq oz. These are contained in the Cata Clavo, Los Pozos,Santa Margarita and Guanajuatito zones. The Guanajuatito zone, with its first estimate, has been significantly expanded from present mining on the 120 and 160 levels to the 390 level and is open to depth and along strike, illustrating that additional mineralization is expected to be found and could add to inventory with systematic and focused drilling.
Mining of the four zones, Cata, Los Pozos, Santa Margarita and Guanajuatito currently accounts for most of the Guanajuato metal production. Underground drilling is ongoing with five drill rigs to delineate new resources on the upper and depth extensions of Los Pozos, the southeast strike extension of Santa Margarita , and lateral and deep extensions at Guanajuatito, as well as deep exploration at Valenciana ( Veta Madre ) and Rayas ( Veta Madre ).
The updated mineral resource estimate for the Guanajuato Mine is valid as of January 31, 2012.
Guanajuato Mine Complex: Mineral Resource Estimations and Contained Silver Equivalent, Gold, and Silver
| Totals Measured
| Totals Indicated
| Totals Meas & Ind
| Totals Inferred
- Measured & Indicated Mineral Resources are estimated using a cut-off grade of 50g/t Ag eq.
- Inferred cut-off grades are 145, 115, 150 and 180 g/t Ag eq for Cata, Pozos, SM and GTTO.
- Gold-silver equivalence ratio for block model purposes was 60.8:1.
- Prices of US$1,150/oz Au and US$17.67/oz Ag were used in calculations.
- A minimum true width of 1.5 m was used for estimates.
- Bulk density is 2.65 t/m3.
- Totals may not agree due to rounding.
- Measured and Indicated Mineral Resources are inclusive of Mineral Reserves.
The Guanajuato Mining District is located in the southern portion of the Mesa Central physiographic province of Mexico within the Sierra de Guanajuato, an anticlinal structure approximately 100 kilometres long and 20 kilometres wide. The Guanajuato District is underlain by rock strata of Mesozoic and Cenozoic age.
The most important phase of mineralization in the Guanajuato district comprises epithermal silver-gold veins contained within northwest-trending, Cenozoic age, faults. The Veta Madre, (Mother Lode), is the most significant mineralized structure in the District, extending for a known strike length of 25 km. Economic mineralization is contained within tabular veins, vein stockworks and breccias. The ore shoots typically range from 1 metre to 15 metres wide, and from 50 to 400 metres along strike, dipping at 40 to 60 degrees southwest.
The Guanajuato Mining District is one of the most prolific and best known silver districts in the world. Silver was first discovered in the La Luz area in 1548, and two years later, an outcrop of the Veta Madre was found near what became the Rayas Mine. Estimates of historic production range from 700 million to 1.5 billion ounces of silver, as well as 4 to 7 million ounces of gold. During the 18th century, the district was reportedly producing one-third of the world's silver. Guanajuato was, for centuries, one of the most affluent cities in Mexico. Countless riches poured out of its silver mines, providing the funds for monumental construction projects throughout the colonial era and leaving a cultural and architectural legacy that continues to draw visitors from all over the world. For this reason, the City of Guanajuato is designated as a UNESCO World Heritage Site.
The Valenciana Mine was once said to be the richest silver mine in the world. Bonanza-style mineralization in the Veta Madre structure in this historic mine was often considered as "direct shipping ore" (to the smelter) as the grades exceed those of the concentrates produced from average ore in the flotation plant. The Spanish developed and controlled mining in the district until 1816 when mining ceased and production facilities were destroyed during the Mexican War of Independence. The now famous Valenciana Shaft had only just been completed and, despite several unsuccessful attempts, it was not until 1868 that the Valenciana Mine was reopened with the help of British capital and steam powered hoists. In the early 1900's American promoters re-opened many of the mines utilizing the newly discovered cyanide process to extract gold and silver. By the mid-thirties there were labour demands for better working conditions and pay such that their properties were turned over to the control of a Mexican owned co-operative in 1939. The Company acquired the Guanajuato operations from this co-operative in 2005.