Three more holes intersect mineralized porphyry at Brama target, Bramaderos Project, paving way for maiden Mineral Resource Estimate in early 2022

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:

https://cornerstoneresources.com/site/assets/files/5827/nr21-17figures.pdf.

HIGHLIGHTS:

• Strong assay results received for holes BMDD009, 010, and 011 at the Brama prospect:
  • BMDD009: 185.3m¹ at 0.4g/t gold, 0.15% copper, (0.64g/t gold equivalent AuEq²) from 116.8m
  • BMDD010: 170.65m at 0.46g/t gold and 0.15% copper. (0.7g/t AuEq) from 311.75m, including
    • 69.6m at 0.65g/t gold, 0.2% copper, (0.97g/t AuEq) from 347m
  • BMDD011: 404.8m at 0.32g/t gold, 0.09% copper, (0.46g/t AuEq) from surface, including
    • 51.3m at 0.54g/t gold, 0.07% copper (0.65g/t AuEq) from surface
• BMDD009 and 010 have further defined the gold-copper mineralized porphyry and intrusive breccia
• BMDD011 has extended the gold-copper mineralized domain to the northwest, below well mineralized trench sampling
• A detailed 3-D geological model has been built for Brama and will underpin a Mineral Resource Estimate (MRE) to be undertaken in early 2022
• Drilling is ongoing with six more holes planned as part of the maiden Mineral Resource drill program

FURTHER INFORMATION:

The results from holes BMDD009, 010 and 011 further highlight the potential for Brama to host a substantial gold-copper porphyry system (Figure 3).

In light of these results Sunstone has defined a drill program to continue through to December 2021, after which all data will be compiled and an initial Mineral Resource Estimate undertaken in early 2022.

Cornerstone VP Exploration, Yvan Crepeau, said:

"We are very pleased with the latest round of results which provide more firm evidence that Brama has the potential to be a large gold-copper mineralized porphyry. Importantly, we are seeing good gold-copper grades from surface.

"An initial Mineral Resource Estimate is a logical next step for the Brama target. Drilling is being guided by robust 3D geological modeling to continue to define the Brama system. In parallel we are re-visiting other targets such as Limon, Playas and Melonal (see Figure 2) with a view to defining additional resources.

"Our plan is to grow the scale of the opportunity at the Bramaderos Project via exploration and mineral resource definition across several porphyry systems."

The Bramaderos Project is ideally located immediately adjacent to the Pan American highway, and within reasonable distance of available hydropower, supporting the economics of potential development opportunities. The project is also supported by nearby commercial airports and significant cities (Loja) and enjoys strong community support.

* The reader is cautioned that there has been insufficient exploration to define a mineral resource at Brama and it is uncertain if further exploration will result in the target being delineated as a mineral resource.

Discussion of Results

Drill hole BMDD009 was drilled in the east and central parts of the main Brama porphyry system (Figures 4 & 5) and intersected a veined porphyry system hosted by diorite. The drill hole further strengthened the interpretation of geology and mineralization between holes BMDD001 and 002.

Drill hole BMDD010 (Figures 4 & 5) intersected the main Brama porphyry stockwork style mineralization and the deeper northern part of the intrusive breccia intersected in BMDD008. The hole drilled orthogonal (at right angles) to previously drilled holes BMDD001, 002 and 005 and has better defined the higher-grade mineralization reported from BMDD001 and historical hole CURI-03, and from the intrusive breccia in hole BMDD005. Hole BMDD010 was drilled at a shallow dip of -30⁰ and therefore the intersections are between 200m and 300m below surface.

Drill hole BMDD011 was drilled towards the northwest from the collar of hole BMDD008 (Figures 4 & 5) and was sited to test the northwest up-dip continuation of the mineralized intrusive breccia body that was intersected at depth in BMDD008, and to test below well mineralized trench intervals of 70m at 0.68g/t gold and 0.16% copper, and 63m at 0.77g/t gold and minor copper.

Assays are pending for holes BMDD012 and 013. Both holes have tested magnetic anomalies to the northwest of the Brama area and have intersected mineralization.

BMDD014 has recently been completed and hole BMDD015 is in progress. Both are testing areas of limited drilling within the higher-grade intrusive breccia.

Table 1: Summary of mineralized intersections in Brama drill holes BMDD009, 010 and 011.

* Gold equivalent values are included in Table 1 to enable comparison, in general terms in an early-stage exploration context, to other large lower-grade gold systems, and to other porphyry systems that are often reported in metal-equivalent terms and are invariably gold and copper deposits, with both metals being targeted by exploration.

Exploration Program at Brama for the Remainder of 2021

Drilling will continue at the Brama target with 1 drill rig through to December 2021. During that period an additional 6 holes for 2,300m are planned to be completed.

This drilling program will form the basis for an maiden (initial) Mineral Resource Estimate (MRE) to be undertaken in early 2022. The goal of this MRE is to establish an initial near surface resource estimate that can then be expanded as exploration continues at Brama and the other nearby targets such as Limon and Melonal (Figure 2). At Brama the >0.4g/t gold equivalent domain is shown in Figure 3 extending from surface to a depth of ~500m as currently modeled and is open at depth. The domain is a plunging ovoid shape with dimensions of 460m (plunge) x 350m (long) x 220m (width).

Planning is also underway for an electrical geophysical survey over the Limon target in late 2021 to early 2022. It is expected that this program will define anomalies for further drill testing in areas where alteration has compromised the magnetic signature of the porphyry systems. The drill targets to be defined will be followed up in 2022. If the results of the survey are promising, then additional surveys may be undertaken at Brama Hill and other targets (Figure 2).

About Bramaderos

Measuring 4,948 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 that crosses the property.

The Bramaderos concession is owned by La Plata Minerales S.A. ("PLAMIN"), which in turn is owned 87.5% by Sunstone (the project operator) and 12.5% by Cornerstone. Cornerstone's 12.5% interest is carried by Sunstone through to the start of commercial production and repayable at Libor plus 2% out of 90% of Cornerstone's share of earnings or dividends from the Bramaderos project (see news release 20-01 dated January 7, 2020).

More information about the property can be found at www.cornerstoneresources.com.

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

Surface and drill core samples from Brama were sent to the LAC y Asociados Cia. Ltda. Sample Preparation Facility in Cuenca, Ecuador for sample preparation. The standard sample preparation for drill core samples (Code PRP-910) is: Drying the sample, crushing to size fraction 70% <2mm and splitting the sample to a 250g portion by riffle or Boyd rotary splitter. The 250g sample is then pulverised to >85% passing 75 microns and then split into two 50g pulp samples. Then one of the pulp samples was sent to the MS Analytical Laboratory in Vancouver (Unit 1, 20120 102nd Avenue, Langley, BC V1M 4B4, Canada) for gold and base metal analysis.

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.

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 northwest Ecuador. Cornerstone has a 20.8% direct and indirect interest in Cascabel comprised of (i) a direct 15% interest in the project financed through to completion of a feasibility study and repayable at Libor plus 2% out of 90% of its share of the earnings or dividends from an operation at Cascabel, plus (ii) an indirect interest comprised of 6.86% of the shares of joint venture partner and project operator SolGold plc Exploraciones Novomining S.A. ("ENSA"), an Ecuadoran company owned by SolGold 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.

Further information is available on Cornerstone's website: www.cornerstoneresources.com and on Twitter. For investor, corporate or media inquiries, please contact:

Investor Relations:
Mario Drolet; Email: Mario@mi3.ca; Tel. (514) 904-1333

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Cautionary Notice:
This news release may contain 'Forward-Looking Statements' that involve risks and uncertainties, such as statements of Cornerstone's beliefs, plans, objectives, strategies, intentions and expectations. The words "potential," "anticipate," "forecast," "believe," "estimate," "intend", "trends", "indicate", "expect," "may," "should," "could", "project," "plan," or the negative or other variations of these words and similar expressions are intended to be among the statements that identify 'Forward-Looking Statements.' Although Cornerstone believes that its expectations reflected in these 'Forward-Looking Statements' are reasonable, such statements may involve unknown risks, uncertainties and other factors disclosed in our regulatory filings, viewed on the SEDAR website at www.sedar.com. For us, uncertainties arise from the behaviour of financial and metals markets, predicting natural geological phenomena and from numerous other matters of national, regional, and global scale, including those of an environmental, climatic, natural, political, economic, business, competitive, or regulatory nature. These uncertainties may cause our actual future results to be materially different than those expressed in our Forward-Looking Statements. Although Cornerstone believes the facts and information contained in this news release to be as correct and current as possible, Cornerstone does not warrant or make any representation as to the accuracy, validity or completeness of any facts or information contained herein and these statements should not be relied upon as representing its views after the date of this news release. While Cornerstone anticipates that subsequent events may cause its views to change, it expressly disclaims any obligation to update the Forward-Looking Statements contained herein except where outcomes have varied materially from the original statements.

On Behalf of the Board,
Brooke Macdonald
President and CEO

Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

¹ The true width of downhole intersections cannot be determined at this time due to insufficient drilling.

² AuEq is calculated on a gold and copper basis only using metals prices at August 30^th 2021, being US$1,814/oz gold, US$4.36/lb copper using the formula: (gold grade in g/t) + 1.6 * (Cu grade in %). No metallurgical recoveries have been applied to exploration results.

³ See footnote 2 above.