Updated exploration model indicates discovery potential at Bramaderos
OTTAWA, Aug. 27, 2019 - Cornerstone Capital Resources Inc. (“Cornerstone” or “the Company”) (TSXV-CGP) (F-GWN) (B-GWN) (OTC-CTNXF) is pleased to provide an update on its Bramaderos gold and copper project in southern Ecuador, which it is exploring together with ASX listed Sunstone Metals Inc. under a farm-in agreement (see “About Bramaderos”, below).
Figures related to this news release can be seen in PDF format by accessing the version of this release on the Company’s website (www.cornerstoneresources.com) or by clicking on the link below:
- Interpretation of regional datasets reinforces the high prospectivity of a broad suite of targets at Bramaderos
- The recent drill results together with other datasets are delivering a robust and predictive model to guide exploration
- Multiple targets identified for both porphyry gold-copper and epithermal gold
- Recent drilling at Bramaderos Main increases Cornerstone’s and Sunstone’s confidence that they will deliver on their discovery goals at Bramaderos
- Detailed soil sampling and ground magnetics surveys are in progress over several additional targets to prepare them for drilling
- Drilling at Limon is ongoing and further drilling is planned for Bramaderos Main to follow-up the highly encouraging drill results received to date from this initial program (see Cornerstone news release dated August 26, 2019)
- High grade gold being targeted at the West Zone epithermal target with the drill rig on site by the end of August. First hole to follow up on 6.9m at 12.7g/t gold within a broader interval of 30m at 3.6g/t gold in trench TR-LB06 (see Cornerstone news release dated November 8, 2017)
With the first few drill holes completed at Bramaderos Main and Limon, the concession-wide exploration data sets have undergone an iterative review and are presented to provide context for the bullish position that Cornerstone and Sunstone hold with regards to the greater Bramaderos Project. Bramaderos is highly prospective for the discovery of porphyry gold-copper and epithermal gold systems.
The series of images in the Figures show our exploration model based on geology, surface geochemistry and geophysics across the Bramaderos concession. We believe these demonstrate that the Bramaderos concession contains numerous highly prospective porphyry gold-copper and epithermal gold systems.
Cornerstone Vice President Exploration, Yvan Crepeau, said:
|“While still in the early stage, the exploration program at Bramaderos has delivered some very good results. The grades and potential scale of the porphyry gold-copper systems are in line with our expectations at this very early stage of exploration. |
“At Bramaderos Main, we are defining a large gold-copper porphyry system and within that are domains of compelling grades and widths. Exploration is a business of chasing these and understanding their geometry, which we are doing, and we remain confident that we will deliver on this early potential.
“We also have multiple other targets such as Limon that are undergoing drill testing as well. And we are also excited to be commencing drilling at the high-grade West Zone epithermal gold target where our first hole will drill underneath 6.9m at 12.7g/t gold within a broader interval of 30m at 3.6g/t gold in trench TR-LB06 (see Cornerstone news release 17-40 dated November 8, 2017).
“We have a lot to do, we are well funded by our farm-in partner Sunstone to progress this work, and we are fortunate to have multiple targets within our concession.”
Limon, Bramaderos Main and West Zone are in the initial drill test phase. Cornerstone and Sunstone are a little over half way through our Phase 1 drilling program of 5,000m. Further drilling will be undertaken at all three prospects as part of this initial Phase 1 program. Additional targets are being refined at Porotillo, Gangue, Playas and El Espiritu.
Exploration Model (see Figure 1):
Integration of exploration datasets is delivering a robust and predictive model to guide exploration.
The Bramaderos concession lies within a geological setting that is typical of porphyry gold-copper and epithermal mineralization environments. Interpretation of detailed topography and regional geology demonstrates a likely eroded granitic and volcanic domain forming a circular subvolcanic ring structure, which is dissected to the east by the Playas river (interpreted here as the Rio Playas Fault Zone) (Figure 1).
The relationship of this ring structure, with the mapped Tangula Batholith, structural mapping from magnetics and geochemical anomalies, and the location of known areas of mineralization forms the basis for a predictive exploration model, with coincident features that support the definition of highly rated exploration targets.
At Bramaderos we have outcropping porphyry and epithermal mineralization, and we have all of the ingredients to support an optimistic view of the discovery potential.
Many targets have been defined. Three of these have been only partly tested with historical drilling and much of that testing is shown to be ineffective based on our recent exploration. Cornerstone and Sunstone have tested 2 targets with only 2 drill holes each, and so are in the very early stages of this exploration program.
Geochemistry (see Figures 2-5):
Porphyry gold-copper targets
Images of the distribution of copper and gold in soil samples across the entire concession show domains of elevated metal values that are prospective for gold-copper porphyry systems.
Figures 2, 3, 4 and 5 clearly display multiple targets defined in several datasets.
- Gold anomalism defines a 4.4km x 2.5km anomaly encompassing Bramaderos Main, Melonal, Porotillo and Gangue porphyry gold-copper targets
- Copper anomalism shows a very similar pattern to gold, and covers an area of 3.7km x 1.3km
- An additional strong copper anomaly is defined at the Playas target
- The weaker geochemical response at Limon is due to the target sitting below altered rock that comprises a ‘lithocap’
- Other elements such as molybdenum, bismuth, selenium, tellurium, sulphur and manganese also define porphyry gold-copper targets through direct association with copper and gold, or through peripheral anomaly positions
The figures also show that within the Bramaderos concession there is an extensive domain that includes all porphyry gold copper targets – clearly defined in the Copper/Zinc image in Figure 4. This domain contains at least 6 porphyry targets. The copper-on-zinc ratio is commonly used to vector towards mineralized systems because copper is more common within those systems and zinc more common peripheral to those systems.
Epithermal Gold targets (see Figure 5):
West Zone is a high-grade epithermal gold target currently defined by surface mapping and trenching. Epithermal gold targets are typically geometrically smaller than porphyry targets, but of significantly higher grade. This is the same pattern we are seeing at West Zone and the first drill hole is due to commence in the next week and will follow up on 6.9m at 12.7g/t gold within a broader interval of 30m at 3.6g/t gold in trench TR-LB06 (see Cornerstone news release dated November 8, 2017).
Detailed interrogation of soil data has defined several other similar targets to West Zone that are currently being followed up. These additional targets are defined in multiple datasets. Figure 5 shows the NE-SW trending Epithermal Target Trend, defined in this case by elevated mercury and showing multiple targets along a corridor at least 4km long.
Detailed soil sampling is in progress over these targets which are collectively referred to as the El Espiritu trend.
Geophysics (Figures 6-8):
It has been established at Bramaderos Main that magnetic bodies correlate strongly with areas of porphyry gold-copper mineralization, and that within those bodies higher grade domains exist that represent potential porphyry gold-copper deposits (Figures 6, 7 and 8).
Porotillo, Gangue and Playas are highly rated on this basis and will be drill tested.
Measuring 4,949 hectares, the Bramaderos project is located approximately 130km from the Loja provincial capital in southern Ecuador. The project is easily accessible via the Pan American Highway which crosses the property.
The Bramaderos concession is owned by Cornerstone subsidiary La Plata Minerales S.A. (“PLAMIN”), which has signed a binding letter agreement with Sunstone Metals Ltd. (formerly Avalon Minerals Ltd.) (ASX: STM), whereby Sunstone has the right to earn a 51% interest in the project by spending US$3.4 million over 3 years to complete a phase 1 drill program. If this first option is earned, Sunstone can go to 70% by funding a bankable feasibility study, and can go to 80% by financing 100% of the cost of construction of a mine and mill (see Cornerstone news release 17-08 dated April 10, 2017).
Cornerstone is currently the operator of the project, with Sunstone having the right to take over as operator once it has earned its initial 51% interest.
Yvan Crepeau, MBA, P.Geo., Cornerstone’s Vice President, Exploration and a qualified person in accordance with National Instrument 43-101, is responsible for supervising the exploration program at the Bramaderos project for Cornerstone and has reviewed and approved the information contained in this news release.
Sampling and assaying
PLAMIN uses a fire assay gold technique for Au assays (FAS-111) and a four acid multi element technique (IMS-230) for a suite of 48 elements. FAS-111 involves Au by Fire Assay on a 30-gram aliquot, fusion and atomic absorption spectroscopy (AAS) at trace levels. IMS-20 is considered a near total 4 acid technique using a 20g aliquot followed by multi-element analysis by ICP-AES/MS at ultra-trace levels. This analysis technique is considered suitable for this style of mineralization.
Standards, blanks and duplicates are inserted ~1/28 samples. The values of the standards range from low to high grade and are considered appropriate to monitor performance of values near cut-off and near the mean grade of the deposit. The check sampling results are monitored and performance issues are communicated to the laboratory if necessary.
Sample security was managed through sealed individual samples and sealed bags of multiple samples for secure delivery to the laboratory by permanent staff of the joint-venture. MS Analytical is an internationally accredited laboratory that has all its internal procedures heavily scrutinized in order to maintain their accreditation. MS Analytical is accredited to ISO/IEC 17025 2005 Accredited Methods.
PLAMIN’s sampling techniques and data have been audited multiple times by independent mining consultants during various project assessments. These audits have concluded that the sampling techniques and data management are to industry standards. All historical data has been validated to the best degree possible and migrated into a database.
Rock samples are collected by PLAMIN’s personnel, placed in plastic bags, labeled and sealed, and stored in a secure place until delivery by PLAMIN employees to the LAC y Asociados ISO 9001-2008 certified sample preparation facility in Cuenca, Ecuador.
Rock samples are prepared crushing to 70% passing 2 mm (10 mesh), splitting 250 g and pulverizing to 85% passing 75 microns (200 mesh) (MSA code PRP-910). Prepared samples are then shipped to MS Analytical Services (MSA), an ISO 9001-2008 laboratory in Langley, BC, Canada, where samples are assayed for a multi-element suite (MSA code IMS-136, 15.0 g split, Aqua Regia digestion, ICP-AES/MS finish) and gold by Fire Assay (MSA code FAS-111, 30 g fusion, AAS finish). Over limit results for Cu (>1%) are systematically re-assayed (MSA code ICF-6Cu, 0.2 g, 4-acid digestion, ICP-AES finish). Gold is assayed using a 30 g split, Fire Assay (FA) and AAS finish (MSA code FAS 111). Over limit results for Au (>10 g/t) are systematically re-assayed (MSA code FAS-415, FA, 30g., gravimetric finish).
Soil samples are dried at low temperature, screened to 80 mesh (MSA code PRP-757), a 15 grams portion is then assayed for a multi-elements suite (MSA code IMS-136, Aqua Regia digestion, ICP-AES/MS finish).
Quality assurance / Quality control (QA/QC)
The MSA Analytical Laboratory is a qualified assayer that performs and makes available internal assaying controls. Duplicates, certified blanks and standards are systematically used (1 control sample every 20-25 samples) as part of PLAMIN’s QA/QC program. Rejects, a 100 g pulp for each rock sample, are stored for future use and controls.
Cornerstone Capital Resources Inc. is a mineral exploration company with a diversified portfolio of projects in Ecuador and Chile, including in the Cascabel gold-enriched copper porphyry joint venture in north west Ecuador.
Exploraciones Novomining S.A. ("ENSA"), an Ecuadorian company owned by SolGold plc and Cornerstone, holds 100% of the Cascabel concession. Subject to the satisfaction of certain conditions, including SolGold's fully funding the project through to completion of a feasibility study, SolGold will own 85% of the equity of ENSA and Cornerstone will own the remaining 15% of ENSA. SolGold is funding 100% of the exploration at Cascabel and is the operator of the project. SolGold shall receive 90% of Cornerstone's distribution of earnings or dividends from ENSA to which Cornerstone would otherwise be entitled until such time as the amounts so received equal the aggregate amount of expenditures incurred by SolGold that would have otherwise been payable by Cornerstone, plus interest thereon from the dates such expenditures were incurred at a rate per annum equal to LIBOR plus 2 per cent until such time as SolGold is fully reimbursed. In addition, Cornerstone has an indirect interest in the project comprised of 9.2% of the shares of joint venture partner and project operator SolGold plc, for a total 22.8% direct and indirect interest in Cascabel.
Further information is available on Cornerstone’s website: www.cornerstoneresources.com and on Twitter. For investor, corporate or media inquiries, please contact:
Mario Drolet; Email: Mario@mi3.ca; Tel. (514) 904-1333
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On Behalf of the Board,
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