18-11 - New heli-magnetics and soil sampling identify additional exploration targets at Bramaderos project in Ecuador
Figures and tables referred to in this 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:
http://www.cornerstoneresources.com/i/pdf/NR18-11Figures.pdf.
Highlights
Further Information Multiple new targets have been defined based on the integration of newly processed detailed heli-magnetic and radiometric survey results and new soil sampling results, and existing targets have been strengthened.
Cornerstone CEO Brooke Macdonald said:
"Systematic exploration work over the entire Bramaderos concession is currently delivering high priority targets to be drill-tested. Most of them have never been drilled. The heliborne geophysical survey brings a new dimension to data integration, confirming previously defined targets at surface and outlining a series of new targets to be explored. This is highly encouraging to see prospective data collected every month since day one on that property and to see how they fit well together into robust mineralization models".
Target Definition The recent acquisition of magnetic and radiometric data across the entire Bramaderos concession provides a key dataset that assists in mapping the geology (faults, alteration types and intrusions). These geophysical datasets underpin the definition and refinement of target areas for porphyry Au-Cu and epithermal Au-Ag mineralization when interpreted in conjunction with geochemical and geological data.
These key datasets have been integrated in a GIS package and targets have been defined based on overlapping and complementary features. The datasets comprise 2-D processed heli-magnetics and radiometrics, current soil sampling results, geological mapping and trenching.
Porphyry Au-Cu targets were defined by identifying deep magnetic anomalies that are surrounded by zones of magnetic lows caused by surrounding alteration around the porphyry centres, and if soil sampled, where there is accompanying Au, Cu and Mo anomalism at surface.
For example, the Limon target as defined by its geophysical signature and overlapping gold and copper soil geochemical anomaly now measures 2km x 1km.
Importantly the West Zone target, which has strong surface evidence of a well mineralized gold epithermal system, also has an associated larger porphyry target.
The soil sampling has been particularly diagnostic in defining epithermal gold targets (so far defined in the central parts of the property) through the identification of element associations similar to those recognized at West Zone.
The defined areas of interest comprise 10 targets for porphyry Au-Cu and an additional 10 targets for epithermal Au-Ag.
This work has also defined a widespread and continuous area of alteration covering over 17 km2 and extending up to 8km x 4km in dimension which coalesces around, and envelopes, many of these target areas. Some of the porphyry and epithermal targets overlap, which is to be expected from a technical perspective (see Figures 1-3).
Three blocks of geophysical data have been defined for 3-D inversion modelling over 7 of the 10 porphyry targets. This work will deliver 3-D models of the magnetic signature of the target areas that can then guide exploration and particularly drilling. This work is expected to take approximately 3 weeks.
Soil sampling and trenching is also ongoing to expand the coverage and to fill in gaps in the current datasets. This work will further strengthen the definition of targets for drilling.
Drill Permitting Update An updated EIA report, recording the positive local response to the EIA process at Bramaderos, has been submitted to the Ministry of Environment. Contact is being maintained with the Ministry and significant effort is being directed towards receiving the permit to allow for drilling.
Preparation of drill access tracks and drill pads at West Zone and Bramaderos Main is underway to allow for an efficient start to drilling once the permit is received. A short list of drill contractors has been identified and the selection of the preferred contractor is imminent.
An inspection by the National Water Secretariat (SENAGUA) has been completed for the water permit process.
About Bramaderos The Bramaderos concession is owned by Cornerstone subsidiary La Plata Minerales S.A. ("PLAMIN"), which has signed a binding letter of intent 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 news release 17-08 dated April 10, 2017).
Qualified Person: 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 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.
About Cornerstone: Cornerstone Capital Resources Inc. is a mineral exploration company with a diversified portfolio of projects in Ecuador and Chile, including the Cascabel gold-enriched copper porphyry joint venture in north west Ecuador. Exploraciones Novomining S.A. ("ENSA"), an Ecuadorean 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 feasibility, SolGold Plc will own 85% of the equity of ENSA and Cornerstone will own the remaining 15% of ENSA. SolGold Plc is funding 100% of the exploration at Cascabel and is the operator of the project.
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On Behalf of the Board, Hugh Brooke Macdonald President and CEO
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