10th Apr 2007 07:45
Berkeley Resources Limited10 April 2007 10 April 2007 INITIAL JORC COMPLIANT RESOURCE OF 11.9 MILLION POUNDS OF U3O8 AT SALAMANCA 1PROJECT The Directors of Berkeley Resources Limited ("Berkeley" or the "Company") (AIM:BKY.L) are pleased to announce that the Company has completed an initial JORCcompliant resource estimate for the Retortillo and Zona 7 uranium depositstotalling 11.9 million pounds of U3O8, at an average grade of 723ppm. There areadditional smaller deposits in the Salamanca 1 area not included in thisestimate. This estimate is based on data from historical drilling campaigns by the Juntade Energia Nuclear (JEN) and Empresa Nacional Uranio S.A. (ENUSA) in the periodfrom the late 1950's to the mid 1980's. Historical data has been verified andre-interpreted with the aid of an eighteen hole diamond drilling programmerecently completed by Berkeley. Resource estimates have been developed by a teamof in-house and consulting geoscientists with calculations based on blockmodelling methods (for Retortillo) and the polygonal method (for Zona 7). The Retortillo deposit is approximately 30 kilometres northeast of the formerENUSA mining operation of Mina Fe at Ciudad Rodrigo and about 65 kilometressouthwest of the provincial capital of Salamanca. Primary (pitchblende andcoffinite) and secondary (uraninite and torbernite) uranium is hosted inandalusite-rich, biotite-altered Ordovician metasediments (phyllites) which havebeen hydrothermally altered to sericite +/- pyrite. At the Zona 7 deposit,approximately 14 kilometres to the north, shallow secondary uranium is hosted bypoorly outcropping, biotite-altered Late Precambrian - Early Cambrian phyllites. Retortillo and Zona 7 were discovered by JEN during regional prospectingprograms in the 1950's and explored by geophysical methods and drilling. A totalof 272 diamond and percussion holes at Retortillo, and 71 at Zona 7 were drilledby JEN and ENUSA through to the 1980's. At Retortillo, drilling defined two mainzones of uranium mineralisation, but did not test the extension of theradiometric anomaly to the northwest, nor close off the mineralisation to thesoutheast. This mineralisation outcrops in several areas, but is usually covered(preserved) by a shallow layer of unconsolidated Tertiary sands, clays andgravels, that thickens to the southeast. It has been intersected at depths of upto 77m. Petrological, mineralogical and metallurgical studies are currentlybeing undertaken on samples of oxidised and primary mineralisation. At Zona 7, two areas of continuous mineralisation have been defined within anarcuate, 1200 x 200m east-west anomaly. Other mineralised areas within theanomaly have been excluded until further drilling is undertaken to resolve someinconsistencies in the historical data. Most of the uranium mineralisation isbelieved to be secondary and occurs within 20m of the surface. The Zona 7anomaly appears to be open and untested to the west and north. This initial resource estimate is an important milestone in the evolution of theCompany. A programme to test the southeast extension of the Retortillo deposithas commenced, and will be followed by drilling of the untested radiometricanomaly to the northwest of the deposit. This work, together with testing ofother targets within the Salamanca I licence (such as Zona 7) will be aimed atassessing global resource potential for the project. In addition a small numberof targeted angle holes within the Retortillo deposit aimed at resolvinguncertainties in the current interpretation, is expected to allowreclassification of much of the resource to the "Indicated" category. Background The Salamanca I Project covers 16,912ha and contains several known uraniumoccurrences, including the Retortillo and Zona 7 deposits. The Junta de Energia Nuclear (JEN) and Empresa Nacional Uranio S.A. (ENUSA)conducted regional and project scale investigations from the late 1950's to the1980's and identified several areas of uranium mineralisation and anomalousradiometrics within the Salamanca I project area. These include the Retortillo,Zona 7, Caridad, Cristina, Zona 35 and Zona 19 occurrences. The Retortillo andZona 7 uranium deposits were selected for further evaluation on the basis ofsize, grade, and depth of mineralisation and completeness of historical data. Recovery, reformatting, compilation and interpretation of the extensive array ofhistorical data over the last 12 months has been supplemented by the recentdrilling programme along selected traverses at Retortillo and check drilling atZona 7. This work has enabled resource estimates for these deposits and alsohighlighted other prospects within the Salamanca I project area. Mineralogical, petrological and metallurgical testwork on oxidized and primarymineralisation from the Retortillo deposit is in progress. Resource Estimation Resource estimates for the Retortillo and Zona 7 uranium deposits have beencarried out by a team of in-house and consulting geoscientists. Assessment andinterpretation of the historical and recent drilling data was undertaken byCompany geologists; assessment of radiometrics and calculation of radiometricequivalent assays were completed by Roger Murphy (former Chief Geologist of theRossing uranium mine); and resource modelling was assisted by McDonald Speijers(a consulting group with 15 years' experience in resource estimations). Theresource for the Retortillo deposit was calculated using block modellingmethods, while the Zona 7 resource was estimated using a plan polygonal method.Resource classification has been carried out in accordance with the JORC Code. Ore Tonnes (Mt) Grade (ppm U3O8) Contained (Mlb U3O8) at 200ppm U3O8 cutoffRetortillo 6.80 720 10.8Zona 7 0.62 760 1.1TOTAL 7.42 723 11.9 Note - for comparative purposes - previously published resource targets atSalamanca 1 (based on historic ENUSA estimates) included an additional 590,000pounds of U3O8 in 3 small deposits, upon which Berkeley has done no work andwhich are therefore not included in the above calculations. Grade was estimated using a calculated U3O8 value. Most historic assays werefluorometric analyses, which were used in preference to the few spectrometricanalyses. Where no chemical analyses were available, radiometric equivalentassays were determined from downhole radiometric surveys using comparisonsbetween available radiometric and chemical data sets. The block model employed block sizes of 12.5m x 12.5m x 2.5m within a wireframedefined by interpretation of the geological and radiometric data. A universalspecific gravity of 2.5 was used for the conversion of volume to tonnes, basedon in-house measurements. The same measure was used by ENUSA in the previousresource estimates. A top cut of 4,000ppm was also applied. When ENUSA commenced exploration of the Salamanca area in the late 1970's andearly 1980's it checked the earlier JEN drill core and samples by re-logging,re-sampling and re-analysing the core and/or JEN sample pulps, and byradiometrically re-logging remnant JEN core. Although no useable drill core orsamples now exist from the JEN and ENUSA drilling, the recent diamond coredrilling by Berkeley has provided a check on both the JEN and ENUSA (diamond andpercussion) drilling. Recent drill results at least equal, or exceed, thehistorical drilling in both grade and intersected widths. The recent holes wereradiometrically logged, and subjected to geological logging, sampling andassaying over the entire core length. Core recoveries were in excess of 93%. The close spacing of historical drilling over most of the Retortillo deposit,and the amount of resulting assay and radiometric data, is sufficient toconsider upgrading the resource category to "Indicated" for most of theRetortillo resource. However, 3D modelling of the deposit reveals someinconsistencies in the interpretation which require resolution by selected angleholes, prior to any reclassification of Retortillo resources. Retortillo Deposit Initial JEN drilling at the northwestern end of the deposit was on a 50 x 50mgrid. After some check/infill drilling at grid centres, ENUSA continued drillingthe southeastern part of the deposit on a 50 x 50m grid. Later drilling to thesoutheast and along the deposit margins was on a 100 x 100m grid with finalstage step-out drilling at 200m centres in the far southeast of the deposit. TheBerkeley check drilling was on 50m centres along grid lines 22E, 61E and 93E. The Retortillo deposit is hosted in andalusite-rich, biotite-spotted schists andappears to be fault-bounded to the northeast and southwest. Chlorite-spottedschists are not known to host any significant mineralisation apart from a thinsecondary horizon. The top of the mineralisation is associated with the upperappearance of sulphides and is generally sharp, horizontal and within 24m of thesurface. The base of mineralisation is irregular and can be associated with thebase of partial weathering. Parts of the mineralisation are overlain by a thin,protective Tertiary cover, which appears to preserve the secondary enrichmentzones. Mineralisation is associated with hydrothermal sericite, pyrite +/-chlorite alteration and averages 15.5m in thickness. The primary mineralisationconsists of pitchblende, coffinite and black oxides incorporated into the mainsteeply dipping schistocity. A secondary enrichment of dominantly autunite andtorbernite occurs as a sub-horizontal layer. The deposit consists of two main blocks separated by the Retortillo Creek. Thenorthwestern block lacks Tertiary cover and the mineralisation has been affectedby weathering and erosion. Although the northern part of the southeastern blockhas been similarly affected by weathering, due to the lack of Tertiary cover,from grid line 60E the Tertiary cover increases to a maximum of around 30m inthe southeastern parts of the deposit. Secondary mineralisation is betterdeveloped beneath this Tertiary cover. An Inferred Resource of 6.8Mt at a grade of 720ppm U3O8 with 10.8Mlbs ofcontained U3O8 has been estimated using a 200ppm U3O8 lower cut-off. Zona 7 Deposit The Zona 7 deposit is 14 kilometres to the north of Retortillo. It occurs withinan arcuate east-west trending radiometric anomaly measuring some 1,100m x 200m.JEN tested the anomalous areas on an incomplete 50 x 50m grid, with more intensedrilling within an area of about 400m x 200m which includes the estimatedresource. Significant mineralisation occurs at very shallow depth ( < 20m) as anear-surface, flat lying layer which tends to dip more steeply to the northeastin the northwestern zone. The discontinuous mineralisation is dominantlygummites and black oxides with significant torbernite and autunite occurring inthermally altered biotite + chlorite spotted schists. The deposit is generally 5to 15m thick, with some intersections in excess of 30m in the northern parts. Significant inconsistencies within the JEN drill data for the eastern half ofthe radiometric anomaly have precluded inclusion of these results in theresource estimate. It is anticipated that these inconsistencies will be resolvedby a short programme of targeted drilling. Resources for the Zona 7 Deposit were estimated using a plan polygonal methodbased on a deposit shape defined by geological, geochemical and radiometricdata. A specific gravity of 2.5 was used for conversion of volume to tonnes(used historically by ENUSA). An Inferred resource of 625,000t at a grade of 760ppm U3O8 with 1.1Mlbs ofcontained U3O8 has been estimated using a 200ppm U3O8 lower cut-off. Ongoing Work Further infill and extension drilling is in progress at Retortillo to confirmand clarify the current resource model, upgrade the resource category and todetermine the southeast extent of the deposit. Additional drilling is planned totest for an extension of the deposit across the Rio Yeltes to the northwest,where a 2km long ground radiometric anomaly equal in strength to the Retortilloanomaly, has never been tested. Further ground radiometrics and drilling will also be undertaken at Zona 7 inorder to extend this resource, and other known anomalies will also beinvestigated with the aim of determining total resource potential within theSalamanca 1 project area. Glossary Autunite: Hydrous phosphate of uranium and calcium occurring as a secondary mineral.Andalusite: A natural alumino-silicate mineral.Arcuate: Curved or bowed.Biotite: A mineral of the mica group, widely distributed in a variety of rocks.Cambrian: A geological time period from 544 to 494 million years ago.Coffinite: A uranium silicate mineral.Chlorite: A platy hydrous silicate related to mica.Fluorometric: A measure of the intensity of fluorescence.Gummites: A mixture of yellow or orange secondary uranium oxides formed by alteration of uraninite.Hydrothermal: Of or pertaining to heated water, to its actions or to products related to its actions.JORC, JORC Code: Joint Ore Reserves Committee, common reference to the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves, 2004.Metasedimentary: General term used to describe sedimentary rocks which have been metamorphosed.Ordovician: A geological time period from 505 to 440 million years ago.Phyllite: A cleaved metamorphic rock with affinities with both slates and schists.Pitchblende: Also called Uraninite. Uranium oxide mineral.Radiometric: Measurement of radioactivity useful in mapping rock formation.Sedimentary: Rocks formed of particles deposited from suspension in water, wind or ice.Sericite: A fine grained version of muscovite micaSpectrometric: A measure of the wavelengths at which absorption bands occur in an absorption spectrum.Tertiary: The first period of the Cenozoic era (after the Mesozoic era and before the Quaternary period), spanning the time between 65 and 1.8 million years ago.Torbernite: Hydrated copper uranium phosphate mineral.Uraninite: An isometric uranium mineral, UO2, that is highly radioactive and the primary ore of uranium. Usually occurs in granular masses or aggregates. The technical content of this report has been reviewed and approved by MrPeter Ellis, a Member of The Australian Institute of Geoscientists and anemployee of Berkeley Resources Limited. Mr Ellis has sufficient experience whichis relevant to the style of mineralisation and type of deposit underconsideration and to the activity which he is undertaking to qualify as aCompetent Person as defined in the 2004 Edition of the 'Australasian Code forReporting of Exploration Results, Mineral Resources and Ore Reserves'. Mr Ellisconsents to the inclusion in the report of the matters based on his informationin the form and context in which it appears. Enquiries - Managing Director: Matt Syme Telephone: +61 417 906 717 Email: [email protected] This information is provided by RNS The company news service from the London Stock ExchangeRelated Shares:
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