Tinka Discovers Tin - Copper Mineralization Beneath High-Grade Zinc at Ayawilca, Peru

VANCOUVER, Nov. 25, 2014 /CNW/ - Tinka Resources Limited ("Tinka" or the "Company") (TSXV: TK) (OTCPK: TKRFF) announces the discovery of tin - copper mineralization in drill holes at the Company's 100%-owned Ayawilca project, central Peru.  The tin mineralization was discovered in the Central Ayawilca area following the re-assaying of nine 2012-2013 drill holes, and one recent 2014 drill hole.  The tin – copper mineralization lies beneath the zinc sulphide mineralization, which is the focus of the current drill program.  Tin (copper) mineralization at Central Ayawilca extends over an area at least 500 metres across, open in all directions, and is cassiterite, the most common ore mineral of tin.    

Dr. Graham Carman, Tinka's President and CEO, stated: "The tin and copper mineralization discovered at Ayawilca is an exciting new development for the project.  Tin is currently valued at US$19,775 per tonne (official price on the LME November 20, 2014) which is close to nine times the current value of zinc, and three times copper.  The potential value of a major tin - copper discovery could therefore be substantial.  We interpret that the zinc mineralization, which occurs with abundant iron minerals, lies on the periphery of a tin - copper porphyry system which is only now being discovered.  Zinc exploration remains the Company's focus. However, it is important for the Company to properly assess the tin - copper potential of Ayawilca in upcoming drill programs, so that the potential value can be unlocked."

Significant tin - copper drill results:

• A13-11:  16.2 metres at 1.03% tin and  0.67% copper from 328.0 metres depth (hole stopped in  mineralization at 344.2 metres) including 2.0 metres at 4.8% tin and 2.1% copper from 330 metres;
• A13-12A: 30.8 metres at 0.54% tin and 0.17% copper from 326 metres depth, including 2.0 metres at 2.5% tin and 0.2% copper from 326 metres depth (hole stopped in mineralization at 356.8 metres);
• A13-01: 76.0 metres at 0.21 % tin and 0.36% copper from 276 metres depth, including 8 metres at 0.94% tin and 0.43% copper.

Tin and copper mineralogy:

• Based on a mineralogical study of eight drill samples from Ayawilca, tin occurs predominantly as cassiterite, the most common ore mineral of tin, with only minor stannite (tin sulphide);
• Almost half of the cassiterite in these samples is coarse-grained (> 0.3 mm), providing the opportunity for possible gravity separation of the coarser tin fractions in any future mining operation;     
• Copper occurs as chalcopyrite, the most common sulphide mineral of copper;
• Tin – copper mineralization occurs in flat lying massive sulphide bodies and stockwork vein systems underlying the zinc sulphide mineralization;

Next steps:

• A new drill hole, A14-27, has recently been completed to 500.70 metres depth, targeting tin-copper mineralization beneath drill holes A13-01 and A13-12A.  Assays are pending;
• Metallurgical tests will be carried out on the tin, including gravimetric and flotation separation tests;
• Exploration drilling for zinc at Ayawilca is continuing:  nine holes have been completed with four holes reported (see news release November 12 2014 , including 148 metres at 4.3% zinc in A14-22) with five holes awaiting assays, and a further seven holes to be completed prior to the Christmas – New Year break.

Discovery of tin mineralization at Ayawilca
Drill samples considered to have 'anomalous' tin values in the ICP multi-element data were re-assayed for ore-grade tin by a standard fusion technique.  The re-assays generally returned significantly higher tin values (i.e., anywhere between 1 and 50 times higher than the original ICP assays). Approximately 700 samples from 18 drill holes were re-assayed for tin by fusion.  Significant tin was found in ten drill holes (nine 2012-2013 holes and one recent 2014 hole) and these intersections are highlighted in Table 1.  The tin and copper intersections were calculated using a 0.2% tin or 0.2% copper cut off. Drill hole collar information for all Ayawilca holes is presented in Table 2. 

Geological controls to the mineralization
A simplified geological map of Ayawilca is shown in Figure 1.  The mineralization at Ayawilca is "blind" beneath 150 metres of flat-lying sandstone. Beneath the sandstone is a sedimentary breccia/siltstone/limestone sequence up to 250 metres thick (Oyon Formation) which is host to the zinc sulphide mineralization, and is the focus of the current drill program. Zinc sulphides (with both high-iron and low-iron sphalerites) generally occur with massive to semi-massive pyrite and/or magnetite with minor pyrrhotite, replacing the siltstones along fracture zones and in the matrix of the sedimentary breccias.  The sedimentary rocks are typically replaced by chlorite, clay, and siderite. 

Tin – copper mineralization occurs at the base of the zinc mineralization in two general styles; (1) disseminated in massive to semi-massive iron-sulphide (pyrrhotite) lenses at the contact between the overlying sedimentary sequence and underlying metamorphics (phyllite), and (2) as quartz sulphide stockwork veinlets hosted by phyllite.  The tin is predominantly cassiterite, with stannite and rare berndtite (both tin sulphides) also noted in mineralogical studies.  Common sulphides occurring with tin are pyrrhotite (magnetic) with lesser chalcopyrite, pyrite, arsenopyrite, and galena.  Alteration recognized within the phyllite is dominated by quartz and sericite, with minor to trace biotite, chlorite and tourmaline.   

Intrusive rocks have not yet been observed at Ayawilca.  We believe that the style of the alteration and mineralization is consistent with the source being derived from an intrusive porphyry system at depth.

A longitudinal west-east section of Ayawilca is shown in Figure 2 showing the styles of mineralization and conceptual targets.

QEMSCAN mineralogy studies
Eight samples were chosen from two metre composite drill samples (crushed to -2 millimetres) from different holes and geological units for QEMSCAN analyses (Quantitative Evaluation of Materials by Scanning Electron Microscopy) at SGS Laboratories in Santiago, Chile.  Table 3 summarises the sample information. The samples sent for QEMSCAN analyses were each between 5 and 10 kilograms, and are considered representative of the 2 metre composite intervals.  In seven of eight samples, a minimum of 75% of the tin is in the form of cassiterite.  In five of these samples (62% of samples) cassiterite represents a minimum of 94% of the tin present.  Table 4 shows the tin minerals present in each sample, and the liberation of the tin minerals. Table 5 shows the size fraction of the tin in the combined 8 samples.  Approximately half of the cassiterite is coarser than 0.30 millimetres, and approximately 75% of the cassiterite is coarser than 0.053 millimetres. 

Colquipucro drill program
Tinka has now completed a 10-hole, 1,500 metre drill program at the Colquipucro silver oxide project, located 2 kilometres north of Ayawilca.  Results of the full program will be released by the end of January 2014. 

The qualified person, Dr Graham Carman, Tinka's President and CEO, and a Fellow of the Australasian Institute of Mining and Metallurgy, has reviewed and verified the technical contents of this release. 

About Tinka Resources Limited

Tinka is a junior resource acquisition and exploration company with projects in Peru.  Tinka's focus is on its 100%-owned Ayawilca and Colquipucro projects in the highly mineralized zinc-lead-silver belt of central Peru, 200 kilometres north of Lima. The Ayawilca project, located 40 kilometres from Peru's largest historic zinc mine, Cerro de Pasco, has the potential to be a major zinc sulphide discovery.  The nearby Colquipucro silver oxide project is a near-surface, sandstone hosted silver oxide deposit with a current inferred resource containing 32 million ounces silver with potential for expansion. 

On behalf of the Board,

"Graham Carman"
Dr. Graham Carman, President & CEO

Forward Looking Statements. Certain information in this news release contains forward-looking statements and forward-looking information within the meaning of applicable securities laws (collectively "forward-looking statements").  All statements, other than statements of historical fact are forward-looking statements. Forward-looking statements are based on the beliefs and expectations of Tinka as well as assumptions made by and information currently available to Tinka's management.  Such statements reflect the current risks, uncertainties and assumptions related to certain factors including, without limitations, capital and other costs varying significantly from estimates, production rates varying from estimates, changes in world metal markets, changes in equity markets, uncertainties relating to the availability and costs of financing needed in the future, equipment failure, unexpected geological conditions, imprecision in resource estimates or metal recoveries, success of future development initiatives, competition, operating performance, environmental and safety risks, delays in obtaining or failure to obtain necessary permits and approvals from local authorities, community relations, and other development and operating risks. Should any one or more of these risks or uncertainties materialize, or should any underlying assumptions prove incorrect, actual results may vary materially from those described herein.  Although Tinka believes that assumptions inherent in the forward-looking statements are reasonable, forward-looking statements are not guarantees of future performance and accordingly undue reliance should not be put on such statements due to the inherent uncertainty therein. Except as may be required by applicable securities laws, Tinka disclaims any intent or obligation to update any forward-looking statement.

Neither the 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 news release.

Notes on core sampling:
All holes are diamond cores with recoveries generally at or close to 100%.  The drill core (typically HQ size) is marked up, logged, and photographed on site.  The cores are then cut in half at the Company's core storage facility with half-cores stored as a future reference.  The other half-core is bagged on average over 2 metre composite intervals and sent to SGS laboratory in Lima for assay in batches.  Standards and blanks are inserted into each batch prior to departure from the Company's core storage facilities.  At the laboratory, samples are dried, crushed to 100% passing 2mm, then 500 grams pulverized for multi-element analysis by ICP using multi-acid digestion. Samples assaying over 1% zinc, lead, or copper are reassayed using precise ore-grade AAS techniques. Samples which assayed approximately 200 ppm tin or greater in the ICP analysis were re-assayed for tin by fusion with sodium peroxide and AAS finish (SGS laboratory method SGS-MN-ME-112). 

Sn =  tin. Cu =  copper.  Zn = zinc. Pb  = lead.  Ag = silver.  Po = Pyrrhotite

All results are in weight percent except silver is grams per tonne. 
* Drill hole ended in tin/copper mineralization                                                                        

Notes on assay results:
Intersections have been calculated on the basis of a 0.2% copper or 0.2% tin cut-off over 6 metre intervals.   

The tin – copper mineralization is interpreted from drill core measurements to be either gently-dipping in massive pyrrhotite sulphide lenses or disseminated within stockwork veinlets in phyllite.  The true widths of the intercepts are believed to be at least 75% of the down-hole widths.

Notes on drill hole data:
Eastings and Northings are based on the PSAD56/18S UTM datum.  The coordinates for the current drill holes are collected via a hand-held GPS and are considered accurate to within a few metres. Drill hole locations from past programs were surveyed with a theodolite or determined by tape and compass from a known survey point. Elevations are taken from a digital topographic model of the project based on a number of known points and are considered accurate to within a few metres.  Azimuth and dip measurements were taken using compass and inclinometer at surface. All holes from A13-10 onwards were down-hole surveyed; small variances in both azimuth and dip do occur down hole. 

Free >= 95%; Lib <95% & >= 80%; Mid <80% & >= 50%; Sub-Mid <50% & >=20%; Locked <20%. 

For the QEMSCAN analyses, 1 kilogram of each primary sample (crushed to -2mm) was further reduced to 0.21 millimetres.  A briquette of each sample was introduced into an electron microscope at SGS Chile for QEMSCAN analysis.  The technique maps the surface of each mineral particle on an automated grid so that composition and texture of each particle can be measured.  Table 4 shows only the tin minerals – the full QEMSCAN analyses provides information on all sulphides as well as silicate and oxide minerals present. 

The tin analysis by size fraction was done by sieving 1 kilogram of each sample (-2mm) to the various mesh sizes with each size fraction assayed for tin. 

Figure 1.  Geology of Ayawilca-Colquipucro highlighting tin-copper and zinc target areas at Ayawilca

Figure 2. Longitudinal section through Ayawilca showing zinc sulphide bodies and tin - copper targets

SOURCE Tinka Resources Ltd.