Coro Mining Corp.

Coro Mining Corp.

July 31, 2008 16:23 ET

Coro Announces Updated Resource Estimate for Its Barreal Seco Deposit, Chile

VANCOUVER, BRITISH COLUMBIA--(Marketwire - July 31, 2008) - Coro Mining Corp. ("Coro" or the "Company") (TSX:COP) is pleased to announce the results of a new resource estimate for the Barreal Seco copper deposit, which is part of its Flores Project, located on the border of Regions II & III in Chile. This estimate incorporates the results of the 2007 drilling program which comprised a total of 43 reverse circulation drill holes for 8,510 meters, aimed at expanding and further defining the in pit resource base. The resource estimate has been completed by NCL Ingenieria y Construccion S.A., Santiago, Chile. Details of the updated resource estimate are presented in Table 1. The Company also reports the results of a column test work program on Barreal Seco oxide and mixed mineralization, conducted at SGS Mineral Services, Santiago, Chile ("SGS").

Alan Stephens, President and CEO of Coro commented, "We are pleased that the drilling we completed in late 2007 has resulted in a substantial increase in the sulphide resources at Barreal Seco. Metallurgical test work on the oxides has confirmed that recoveries in excess of 70% are achievable albeit at relatively high sulfuric acid consumptions. We will now proceed to evaluate various alternatives for the development of a heap leach operation at Barreal Seco followed potentially by a flotation operation, based on this expanded resource."

Updated Resource Estimate

An updated mineral resources block model was produced for the Barreal Seco deposit, using information from Coro's 2006 and 2007 drilling campaigns and from earlier Rio Tinto and Atna Resources drilling.

Table 1: Mineral Resources Estimate at a cutoff of 0.3% Cu T (total copper)

Tonnes Cu T Cu T Metal Cu Sol. Cu Sol Metal
Oxides x 1000 % lb x 1000 % lb x 1000
Measured 7,397 0.60 97,789 0.38 61,896
Indicated 21,031 0.53 247,698 0.33 150,860
Mea+Ind 28,428 0.55 345,487 0.34 212,757
Inferred 2,564 0.44 25,029 0.28 15,993
Mixed - -
Indicated 4,361 0.54 51,967 0.20 19,701
Inferred 450 0.42 4,123 0.18 1,804
Sulphide - -
Indicated 59,434 0.53 689,578 -
Inferred 15,046 0.41 136,634 -
Total - -
Measured 7,397 0.60 97,789 0.38 61,896
Indicated 84,825 0.53 989,243
Mea+Ind 92,222 0.53 1,087,032
Inferred 18,060 0.42 165,785

The key parameters used for this resource estimate were:

- Coro geologists prepared a geological interpretation, which defined High Grade and Low Grade mineralized zones. These were then divided into oxide, mixed and sulphide categories. Statistical and contact analysis showed good distinction between the High Grade and Low Grade zones, and so these two populations were separated for geostatistical purposes. Mixed and oxide categories showed similar characteristics, which allowed for their grouping. The sulphide zone was estimated separately.

- Samples representative of the mineralized zones were selected using the geology solids, complemented with manual selection.

- Correlograms were made for each population, and ordinary kriging of the Cu T (total copper) was performed, after capping of the highest 1% of the population.

- Solubility ratios were calculated using the inverse distance squared method, which then allowed for the estimation of Cu Sol (Soluble copper) by applying this ratio to the kriged value of CuT.

- The rock density was kriged using values assigned to each sample, according to the lithology logged. The averages per lithological type were defined using the results of the 57 available specific gravity measurements.

- Indicated resources were defined for those blocks estimated with at least two drillholes within the range corresponding to 80% of the variance. Measured resources were defined only for oxide resources, using kriging variance lower than 0.13, which was a threshold defined after visual inspection of the relationship between the blocks and the drillholes.

- Results were validated using drift analysis and comparison with Nearest Neighbour estimates. Good agreement between sample composites, kriged and Nearest Neighbour estimates was observed, validating the results.

- Whittle optimization, using a copper price of US$2.50/lb Cu was performed, to determine material which could have reasonable prospects of economic extraction

Compared to the previous mineral resource estimate for Barreal Seco, completed in February 2007, which was done at a copper price of US$1.35/lb Cu, the total copper contained in the indicated resource category has increased from 22 million lbs to 690 million lbs for sulphide and from 17 million lbs to 52 million lbs for mixed. The total copper contained in the measured and indicated oxide resource categories increased marginally from 325 million lbs to 345 million lbs.

Metallurgical Testwork Results

The Company has completed a program of metallurgical test work on the oxide and mixed material using drill core from the Barreal Seco deposit at SGS. A total of 5 composites derived from 641 individual drill core samples representative of three metallurgical zones of oxide and mixed mineralization present at the property were produced, and mineralogical analysis, crushability tests (low energy impact test) and bottle roll tests were completed for each composite. The results of this initial test work were then used to construct a total of 10 columns, aimed at assessing copper recoveries and acid consumptions at differing crush sizes, acid curing conditions in agglomeration, and column heights.

Mineralogical analysis showed that the principal oxide mineral present is atacamite, with subordinate chrysocolla, while the principal sulphide minerals are chalcopyrite, chalcocite and covellite. The mineralization was shown to have a low crushing work index. A summary of the mineralogical analysis and crush test is shown in Table 2, and the head assay results in Table 3.

Table 2: Mineralogical Analysis and Crushing Work Index

Mineralogical Analysis Work Index
Composite oxide primary mixed leached kWh/t
Zone 1 95.0% 0.9% 4.1% 0.0% 6.1%
Zone 2 67.0% 0.0% 32.0% 0.9% 6.6%
Zone 3 87.0% 0.0% 13.0% 0.0% 8.0%
Zone 1 / 2 50% Zone 1 / 50% Zone 2
Zone 1 / 2 / 3 20% Zone 1 / 40% Zone 2 / 40% Zone 3

Table 3: Head Assays

Head Assays Solubility
%CuSol %
Composite %Cu T %Cu Sol %Cu CN %Cu Res %Fe T +CN Soluble
Zone 1 0.78 0.58 0.07 0.12 25.7 0.65 83.3%
Zone 2 0.68 0.36 0.19 0.12 21.5 0.55 80.9%
Zone 3 0.79 0.47 0.18 0.l3 16.6 0.65 82.3%
Zone 1 / 2 0.71 0.43 0.13 0.14 21.8 0.56 78.9%
Zone 1 / 2 / 3 0.71 0.41 0.14 0.16 22.9 0.55 77.5%

All columns were run for a period of 147 days at an irrigation rate of 10 L/h/m2, with the results shown in Table 4 below

Table 4: Column Testwork Results

Column Testwork results
Curing Net Acid
Column Composite Col Height P80 acid % Recovery Cons
# m minus Kg/t (0f Cu T) Kg/t
1 Zone 1 6 1/2" 10 77.6% 63.4
2 Zone 1 6 1/2" 20 74.0% 73.7
3 Zone 1 6 3/4" 20 77.6% 73.3
4 Zone 2 6 1/2" 20 59.7% 76.4
5 Zone 2 6 3/4" 20 61.8% 76.6
6 Zone 3 4 3/4" 20 71.2% 107.5
7 Zone 1 / 2 6 1/2" 20 72.1% 74.6
8 Zone 1 / 2 6 3/4" 20 71.9% 74.8
9 Zone 1 / 2 / 3 6 1/2" 20 69.0% 75.7
10 Zone 1 / 2 / 3 6 3/4" 20 65.4% 75.5

SGS concluded that:

- the dominantly oxide Zones 1 and 3 composites had broadly similar recoveries

- the lower recoveries in the Zone 2 and Zone 1/2/3 composites reflect their higher sulphide content

- there is no clear impact on recoveries of differing granulometry

- reducing the curing acid from 20 to 10kg/t (column 1), reduced acid consumption from 73.7 to 63.4 kg/t, while maintaining copper recovery

- the high acid consumption in column 6 is partly a function of erroneously using the same irrigation rate for a 4m column as for the other 6m columns. The Zone 3 composite also has a higher calcite and gypsum content

In general, SGS anticipate that recoveries could be increased with greater than 147 days of leach time and that acid consumptions could potentially be reduced by agglomerating with less acid.

Future Work Program

The oxide column test work has confirmed that recoveries in excess of 70% are achievable at Barreal Seco and there is potential to reduce acid consumptions to the 60-65kg/t range. Further work will focus on assessing the impact of current high sulphuric acid prices and regional power costs on the economics of the oxide resource, including the potential for a smaller scale heap leach operation based on a higher grade core to the deposit. The Company will also assess the potential for a low capital cost SX only operation producing copper sulphate, as an alternative to producing copper cathode via SXEW.

With the definition of a larger sulphide resource at Barreal Seco, the Company intends to conduct flotation test work which given the specularite content of the mineralization, will include test work on recovering iron. Internal evaluations by the Company have demonstrated that sea water is the most likely water source for an operation at Barreal Seco, which is located some 70km from the coast.

Qualified Person Notes

The mineral resource estimates contained in this news release have been prepared in accordance with National Instrument 43-101 Standards of Disclosure for Mineral Projects ("NI 43-101"). The technical information in this news release, including the information that relates to geology, mineralization, drilling, and mineral resource estimates on the Barreal Seco deposit, is based on information prepared under the supervision of, or has been reviewed by Alan Stephens, FIMMM, President and CEO, a geologist with more than 32 years of experience employed by Coro Mining. The foregoing person is a "qualified person" for the purposes of NI 43-101 with respect to the geology, mineralization and drilling being reported on.

The "qualified person" responsible for the independent resource estimate for resources at Barreal Seco was Rodrigo Mello a geologist with more than 22 years of experience of NCL Ingenieria y Construccion S.A. The "qualified person" responsible for supervising the metallurgical testwork and reporting was Heriban Soto, MSc, PhD, and Technical Manager from SGS.

The technical information has been included herein with the consent and prior review of the above noted qualified persons. The qualified persons have verified the data disclosed, including sampling, analytical and test data underlying the information or opinions contained herein.

All mineral resources have been estimated in accordance with the definition standards on mineral resources and mineral reserves of the Canadian Institute of Mining, Metallurgy and Petroleum referred to in National Instrument 43-101, commonly referred to as NI 43-101. U.S. reporting requirements for disclosure of mineral properties are governed by the United States Securities and Exchange Commission (SEC) Industry Guide 7. Canadian and Guide 7 standards are substantially different. This News Release uses the terms "measured," "indicated" and "inferred" resources. Mineral resources which are not mineral reserves do not have demonstrated economic viability. We advise investors that while those terms are recognized and required by Canadian regulations, the SEC does not recognize them. Inferred mineral resources are considered too speculative geologically to have economic considerations applied to them that enable them to be categorized as mineral reserves.


Alan Stephens, President and CEO

About Coro Mining Corp.:

The Company was founded with the goal of building a mining company focused on medium-sized base metals deposits in Latin America. The Company intends to achieve this through the exploration for, and acquisition of, projects that can be developed and placed into production and it has established an experienced development and exploration team to accomplish this. Coro has two main properties; Flores, in Chile and San Jorge, in Argentina, an option to acquire the Cerro Negro copper mine in Chile, as well as other exploration properties located in Chile.

This news release includes certain "forward-looking statements" under applicable Canadian securities legislation. Such forward-looking statements or information, including but not limited to those with respect to the prices of copper, estimated future production, estimated costs of future production, permitting time lines, involve known and unknown risks, uncertainties, and other factors which may cause the actual results, performance or achievements of the Company to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements or information. Such factors include, among others, the actual prices of copper, the factual results of current exploration, development and mining activities, changes in project parameters as plans continue to be evaluated, as well as those factors disclosed in the Company's documents filed from time to time with the securities regulators in the Provinces of British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland and Labrador.

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