- Significant land package (over 32,000 hectares) located within a highly prospective mineral belt in the state of Chihuahua; 26 km from the historic silver mining city of Parral;
- Property has good road access, gentle topography, power and water sources nearby;
- No known modern exploration or previous drilling conducted on the property until Northair in 2009;
- The mineralized system at La Cigarra has been traced over approximately 6.5 kilometres and outcrops at surface as a silver soil anomaly with numerous historic surface workings along strike;
- Results from 154 drill holes totaling over 25,000 metres clearly outline a continuously mineralized portion with a strike length of 3.6 kilometers encompassing the La Borracha, San Gregorio and Las Carolinas Zones; click the following link to view the comprehensive results of all the drill holes completed to date: La Cigarra Drill Results;
- Initial resource estimate incorporates data from 143 of 154 drill holes competed within a potentially surface minable mineralized area comprised of the San Gregorio and Las Carolinas mineralized zones, which combined form a total strike length of 2.1 kilometres;
- Property's initial NI 43-101 resource estimate hosts 50.4 million ounces of silver in the Measured & Indicated categories grading 76 g/t silver and 3.5 million ounces of silver in the Inferred category grading 61 g/t silver constrained by a Whittle pit shell at an economic cutoff grade of 30 g/t silver, and metallurgical recoveries of 84% silver; click the following link to view the Technical Report: NI 43-101 La Cigarra Technical Report;
- Significant quantities of mineralized material existing along strike and down dip were excluded from the resource estimate in areas where drill-hole density was not sufficient to bring mineralization into the pit shell boundary;
- Further drilling within and adjacent to the optimized pit, which has a current strip ratio estimated at 3.28:1, could potentially add significant silver ounces to the current resource estimate;
- The purchase of surface rights and a twenty (20) year lease agreement signed with the Ejido Estanzuela allows Northair to conduct exploration activities on the Property as well as future construction, mining and processing.
The resource estimate was calculated based on results from 143 of 154 holes totaling 25,576 metres drilled along the open ended La Cigarra mineralized system which has a defined strike length of at least three (3) kilometres. The 143 holes included in the Property's initial resource estimate were positioned within a potentially surface minable area comprised of the San Gregorio and Las Carolinas mineralized zones, which combined form a total strike length of 2.1 kilometres. The resource estimate was constrained by a WhittleTM pit shell at an economic cutoff grade of 30 g/t of silver, and considers metallurgical recoveries of 84% silver. A summary of the mineral resource estimate contained in the resource shell calculated by ACS at a 30 g/t silver cut-off grade is listed below:
|Category||Tonnes*||Ag (g/t)||Au (g/t)||Pb (%)||Zn (%)||Ag Oz||Au Oz||Pb Lbs||Zn lbs|
|M + I||20,755,700||76||0.06||0.10||0.15||50,494,000||40,100||46,086,200||67,689,700|
The mineral resources of the La Cigarra Project are sensitive to cut-off grade. To illustrate this, the block model quantities and grade estimates within the conceptual pit are presented in the following table at different cut-off grades.
|CLASS||Cut-off||Tonnes (000)||Ag (g/t)||Ag (oz)||Au (g/t)||Pb (%)||Zn (%)|
|Measured||>100 Ag g/t||803||137||3,548,500||0.08||0.14||0.17|
|> 50 Ag g/t||3,571||85||9,741,200||0.07||0.11||0.18|
|> 40 Ag g/t||4,753||75||11,434,300||0.06||0.11||0.17|
|>30 Ag g/t||6,235||65||13,090,800||0.06||0.1||0.16|
|>20 Ag g/t||8,220||56||14,676,900||0.06||0.08||0.14|
|> 10 Ag g/t||11,689||43||16,301,200||0.05||0.07||0.12|
|Indicated||>100 Ag g/t||3,578||156||17,968,000||0.08||0.15||0.19|
|> 50 Ag g/t||9,235||104||30,834,800||0.07||0.12||0.17|
|> 40 Ag g/t||11,273||93||33,763,100||0.06||0.11||0.16|
|>30 Ag g/t||14,521||80||37,402,800||0.06||0.1||0.14|
|>20 Ag g/t||19,539||66||41,381,600||0.06||0.09||0.13|
|> 10 Ag g/t||27,714||51||41,381,600||0.05||0.07||0.11|
|Inferred||>100 Ag g/t||160||139||717,400||0.06||0.15||0.18|
|> 50 Ag g/t||936||82||2,467,000||0.06||0.12||0.15|
|> 40 Ag g/t||1,252||73||2,920,200||0.06||0.11||0.14|
|>30 Ag g/t||1,780||61||3,515,900||0.05||0.1||0.12|
|>20 Ag g/t||2,497||51||4,091,200||0.05||0.09||0.11|
|> 10 Ag g/t||3,386||41||4,689,300||0.05||0.08||0.09|
The development of the comparative tables above has relied on the work of experts. The following factors should also be noted:
- Mineral resources were estimated in conformance with the CIM Mineral Resources definitions referred to in National Instrument 43-101, Standard of Disclosure for Mineral Properties;
- The resource estimate considered the results of 154 drill holes totaling (25,576 metres) and was calculated by using 143 of these holes;
- Mineral resources were estimated by ordinary kriging in 10x10x10 metre blocks. Grades were capped to 500 g/t silver in the high grade portion of the mineralization:
- Mineral resources were classified as Measured if at least three (3) drill holes were found within a 75 x 50 x 25 metre search radius. Blocks were classified as Indicated if two (2) drill holes were found within a 75x50x25 metre radius and block were classified as Inferred if at least three (3) drill holes were found within a 100x75x30 metre search radius;
- The "reasonable prospects for economic extraction" requirement generally implies that the quantity and grade estimates meet certain economic thresholds and that the mineral resources are reported at an appropriate cut-off grade taking into account extraction scenarios and processing recoveries. In order to meet this requirement, ACS considers that major portions of La Cigarra mineralization are amenable for open pit extraction;
- In order to determine the quantities of material offering "reasonable prospects for economic extraction" by an open pit, ACS, with the assistance of JDS, used Whittle(tm) pit optimization software and reasonable mining assumptions to evaluate the proportions of the block model (Measured, Indicated and Inferred blocks) that could be "reasonably expected" to be mined from an open pit;
- The optimization parameters, found in the table below, were selected based on experience and benchmarking against similar projects. The reader is cautioned that the results from the pit optimization are used solely for the purpose of testing the "reasonable prospects for economic extraction" by an open pit and do not represent an attempt to estimate mineral reserves. There are no mineral reserves on the La Cigarra Project. The results are used as a guide to assist in the preparation of a mineral resource statement and to select an appropriate resource reporting cut-off grade.
|Silver Price||$ 29.20||US$ per ounce|
|Lead Price||$ 1.00||US$ per pound|
|Zinc Price||$ 0.95||US$ per pound|
|Mining Cost||$ 2.00||US$ per tonne mined|
|Processing (Sulphide material)||$ 15.00||US$ per tonne of sulphide feed|
|Processing (Oxide Material)||$ 12.00||US$ per tonne of oxide feed|
|General and Administrative||$ 1.00||US$ per tonne of feed|
|Overall Pit Slope||45||degrees|
|Silver Flotation Recovery||84||Percent|
|Lead Flotation Recovery||75||Percent|
|Zinc Flotation Recovery||60||Percent|
|Silver Leach Recovery||90||Percent|
|Silver Payable in Lead Conc.||95||Percent|
|Silver Payable in Zinc Conc.||70||Percent|
|Silver Dore Payable||100||Percent|
|Potential In-Situ Grade||Potential Contained Metal|
|Category||Tonnes(000)||Ag (g/t)||Au (g/t)||Pb (%)||Zn (%)||Ag (oz)|
|Exploration Potential||3,000 to 4,500||65 to 75||~0.06||0.09 to 0.1||0.13 to 0.14||6,000,000 to 10,000,000|
The long section (shown below) covering the San Gregorio and Las Carolinas zones demonstrates the meaningful drill intersections that encountered mineralization below and adjacent to the optimized pit, which were not included in the calculation of the resource estimate.
Furthermore, considerable resource exploration potential exists along the open continuous six (6) kilometre long La Cigarra mineralized system. This potential is in part supported by soil sampling along trend of the system, comprising the La Borracha Zone to the north (where nine (9) drill holes have intercepted significant silver mineralization) and the Las Venadas Zone to the south (which has returned surface silver values of up to 233 g/t silver over 2.5 metres). The defined target zone at Las Venadas covers an area of approximately 230 metres by 90 metres.
In addition, numerous other target areas within the remaining 32,000 hectare land package could host significant mineralization as evidenced by a cluster of historic workings and mineralized grab samples obtained from preliminary prospecting.
The samples for the test work were collected by the Company from the San Gregorio Zone and classified into sulphide and oxide material. The sulphide samples were selected from 13 core drill holes, while the oxide samples were collected from 4 core drill holes. A flotation and cyanide leaching flow sheet was developed in order to achieve the optimum recovery of silver and base metals.
For sulphide material, silver was primarily recovered in a lead flotation concentrate. Initial recoveries of up to 73% of the silver and 70% of the lead were achieved at a primary grind size of 75 microns from material containing 68 g/t silver and 0.15% lead. In a separate test, about 85% of the silver in the lead cleaner tailings was extracted in a 96-hour carbon-in-leach process after regrinding to 11 microns. Based on these results, there is potential to recover approximately 85% of the total silver from material in a combined flotation-leaching flow sheet. This will be investigated further in future metallurgical programs. Preliminary assessment of the lead concentrate containing 48% lead and 22,600 g/t silver indicates that it would be marketable to smelters.
For oxide material, the silver is more amenable to whole ore leaching than flotation. Approximately 90% of the silver was extracted from material containing 57 g/t silver in 48 hours of whole ore cyanidation at a grind size of 94 microns.
These results indicate that a combined flotation-leaching flow sheet would achieve maximum silver recovery and could apply to both the sulphide and oxide ores.
Preliminary testing also indicated the potential for producing a zinc concentrate from the lead flotation tailings. A zinc flotation test on the tailings recovered about 55% of the zinc and 6% of the silver in a concentrate grading 57% zinc and 1,764 g/t silver grade. The material sample contained 0.12% lead, 0.15% zinc and 44 g/t silver.
The Company is planning further testing to confirm the process flow sheet and metallurgical performance with samples to be collected representing material from both the San Gregorio and Las Carolinas zones.
The metallurgical program was carried out by G&T Metallurgical Services of Kamloops, B.C., through the consulting firm of JDS Energy & Mining Inc., under the supervision of Hoe Teh, P.Eng, a Qualified Person as defined by NI 43-101
The La Cigarra mineralized system is hosted within sedimentary rocks and can be traced in outcrop for upwards of 6.5 kilometres on strike. The mineral system strikes northwest and dips moderately northeast and mirrors the strike and dip of the host sediments. Mineralization is spatially associated with narrow diorite to granodiorite sills. Silver and base metals occur in sulfides hosted within quartz-vein stockwork zones and silicified breccias containing disseminated sulphides. The recognition of disseminated style of mineralization strongly enhances the economic potential of the Project.
Northair is currently conducting a core drill program at La Cigarra. The program will total over 5,000 metres of drilling and is designed to expand the La Cigarra mineral resource by targeting down-dip and on strike projections of mineralization at the north end of the San Gregorio Zone and to the south of the Las Carolinas Zone. Positive results from drilling within and adjacent to the optimized pit could add significant amount of silver ounces to the current mineral resource estimate and lower the estimated 3.28:1 strip ratio. On trend and further to the south, the program will include 1,700 metres of exploration drilling to test significant soil and rock geochemical anomalies and historic mine workings identified at the Las Venadas and Las Chinas targets. These targets have never been drilled and are underlain by the same stratigraphy that hosts mineralization at the San Gregorio and the Las Carolinas zones, and could potentially extend the La Cigarra mineralized trend an additional two (2) kilometers.
Northair is also planning further metallurgical testing to confirm the process flow sheet and metallurgical performance with samples to be collected representing material from both the San Gregorio and Las Carolinas zones.