REG - Berkeley Energia - Increase in grade expected to boost economics <Origin Href="QuoteRef">BKY.AX</Origin> - Part 3
03/03/2016 18:04
- Part 3: For the preceding part double click ID:nRSG0809Lb
associated with brittle deformation. Uraninite and coffinite are the primary uranium minerals. Secondary uranium mineralisation is developed in "supergene-like" tabular
zones corresponding to the depth of weathering. Most of the mineralisation is hosted within totally and partially weathered metasediment. This deposit falls into the
category defined by the International Atomic Energy Association (IAEA) as Vein Type, Sub Type Iberian Type.
Drill hole Information A summary of all information material to the understanding of the exploration results including a tabulation of the following information for all Material drill holes:o easting and northing of the drill hole collaro elevation or RL (Reduced Level - elevation above sea level in metres) of the drill hole collaro dip and azimuth of the holeo down hole length and interception deptho hole length. No additional drilling data is available. All drilling data has been presented in previous ASX releases, with the most recent being April 2015.
If the exclusion of this information is justified on the basis that the information is not Material and this exclusion does not detract from the understanding of the report, the Competent Person should clearly explain why this is the case. No changes have been made to any of the drilling data reported in previous ASX releases. The purpose of this release is presentation of an update to the mineral resource
estimate based on improved definition of the mineral resource at the selected mining unit block size of 5 x 5 x 6m (X x Y x Z).
Data aggregation methods In reporting Exploration Results, weighting averaging techniques, maximum and/or minimum grade truncations (eg cutting of high grades) and cut-off grades are usually Material and should be stated. Previously reported drill intersections are based on chemical assay data and are calculated using a 200ppm U3O8cut-off, no high grade cut, and may include up to 2m of
internal dilution.
Where aggregate intercepts incorporate short lengths of high grade results and longer lengths of low grade results, the procedure used for such aggregation should be stated and some typical examples of such aggregations should be shown in detail. High grade intervals that are internal to broader zones of uranium mineralisation are reported as included intervals.
The assumptions used for any reporting of metal equivalent values should be clearly stated. No metal equivalent values were used.
Relationship between mineralisation widths and intercept lengths These relationships are particularly important in the reporting of Exploration Results. If the geometry of the mineralisation with respect to the drill hole angle is known, its nature should be reported. All drilling was planned in such a way as to intersect expected mineralisation in a perpendicular manner. The uranium mineralisation is interpreted to be flat lying to
shallowly dipping so all of the RC holes were drilled vertically.
If it is not known and only the down hole lengths are reported, there should be a clear statement to this effect (eg 'down hole length, true width not known'). The reported down-hole intervals are interpreted to approximate true widths.
Diagrams Appropriate maps and sections (with scales) and tabulations of intercepts should be included for any significant discovery being reported These should include, but not be limited to a plan view of drill hole collar locations and appropriate sectional views. Appropriate diagrams, including a drill plan and cross sections, are included in the main body of this release.
Balanced reporting Where comprehensive reporting of all Exploration Results is not practicable, representative reporting of both low and high grades and/or widths should be practiced to avoid misleading reporting of Exploration Results. No new exploration results are available. All drilling and other information has been reported in previous ASX releases.
Other substantive exploration data Other exploration data, if meaningful and material, should be reported including (but not limited to): geological observations; geophysical survey results; geochemical survey results; bulk samples - size and method of treatment; metallurgical test results; bulk density, groundwater, geotechnical and rock characteristics; potential deleterious or contaminating substances. Down-hole gamma logging of all Berkeley holes was undertaken to provide eU3O8 data. Comparison of eU3O8 data with chemical assay data have shown that on average eU3O8
tends to underestimate at higher grades (>500ppm) and overestimate at lower grades (<200ppm). The Mineral Resource Estimate (MRE) reported in this release was estimated
using chemical assay data as the primary method for grade estimation in the modelling process. eU3O8 data was used for grade estimation process when chemical assay data
was not available. The Company has reported the results of a PFS for the Salamanca Project which includes the Retortillo deposits (refer ASX Announcement dated 26
September 2013). The PFS included hydrogeological, geotechnical, mining, metallurgical and process engineering studies, as well as environmental impact assessments.
Further work The nature and scale of planned further work (eg tests for lateral extensions or depth extensions or large-scale step-out drilling). Further work planned for the Retortillo deposits includes additional infill drilling focused on improving geological confidence and resource classification of open pit
areas scheduled to be mined post the initial two years of production (based on the PFS).Geological studies will include detailed interpretation of lithology, structure
and weathering and an assessment of potential relationships between these factors and uranium grade distribution. Further work is also planned on a number of other
exploration targets within the Retortillo Region.
Diagrams clearly highlighting the areas of possible extensions, including the main geological interpretations and future drilling areas, provided this information is not commercially sensitive. N/A
Further work planned for the Retortillo deposits includes additional infill
drilling focused on improving geological confidence and resource
classification of open pit areas scheduled to be mined post the initial two
years of production (based on the PFS).Geological studies will include
detailed interpretation of lithology, structure and weathering and an
assessment of potential relationships between these factors and uranium grade
distribution. Further work is also planned on a number of other exploration
targets within the Retortillo Region.
Diagrams clearly highlighting the areas of possible extensions, including the
main geological interpretations and future drilling areas, provided this
information is not commercially sensitive.
N/A
Section 3 Estimation and Reporting of Mineral Resources
(Criteria listed in the preceding section also apply to this section.)
Database integrity Measures taken to ensure that data has not been corrupted by, for example, transcription or keying errors, between its initial collection and its use for Mineral Resource estimation purposes. Drill hole data is stored in a password protected relational database (Access). Drill data recorded in digital Excel templates is transferred to the database by the
project geologist who is responsible for reviewing and validating the data. Assay data is received from the external laboratories in digital format and is loaded directly
into the database after QA/QC has been checked and validates the rest of assays.Geological logging is restricted to appropriate codes relevant to the local geology,
mineralisation, weathering and alteration setting. A copy of the master database is linked to Surpac mining software for Mineral Resource Estimation.
Data validation procedures used. Database validation checks including collar survey position, down hole survey control, assay limits, eU3O8 profiles, sample intervals and logging codes are completed
prior to the data being transferred to the master database.
Site visits Comment on any site visits undertaken by the Competent Person and the outcome of those visits. Sampling techniques and procedures, as well as QA/QC data, are reviewed internally an ongoing basis. Malcolm Titley, (CP, Geology Consultant, Maja Mining Limited) has
reviewed the sampling techniques, procedures, data and resource estimation methodology. He has undertaken a number of site visits, the latest being in August 2015, to
review and inspect the application of these procedures. He concludes that the sampling and analytical results available are appropriate for estimation of the Mineral
Resource.
If no site visits have been undertaken indicate why this is the case. Site visits have been undertaken.
Geological interpretation Confidence in (or conversely, the uncertainty of) the geological interpretation of the mineral deposit. The confidence of the geological interpretation is appropriate for the current level of resource estimation. The resource is defined within mineralised envelopes which
encompass all zones of significant mineralisation.
Nature of the data used and of any assumptions made. Geology and mineralisation interpretation is based on geological logging and sample assays derived from RC and DD drilling, along with cross sectional interpretations
which include surface mapping information and geophysical studies.
The effect, if any, of alternative interpretations on Mineral Resource estimation. Structural studies show dips of structures vary between 50° and 80° however; the uranium mineralisation has undergone supergene remobilisation and is interpreted to be
flat lying to shallowly dipping and generally within 100m from surface.
The use of geology in guiding and controlling Mineral Resource estimation. On the deposit scale the uranium grade is controlled by both lithology and structure, while on a local scale the grade is interpreted to be influenced by supergene
processes.
The factors affecting continuity both of grade and geology. Geological logging and uranium assay of samples from drill holes has demonstrated the continuity of the grade and lithology between mineralised sections. Breaks in
continuity are likely due to structural offsets, some of which have been observed or interpreted from surface mapping.
Dimensions The extent and variability of the Mineral Resource expressed as length (along strike or otherwise), plan width, and depth below surface to the upper and lower limits of the Mineral Resource. The main deposit (including a small satellite zone) covers an area of approximately 3km by 0.6km. A second smaller deposit to the NW covers an area of approximately 2.3km
by 0.2km. The mineralisation at both deposits generally occurs within 100m of surface.
Estimation and modelling techniques The nature and appropriateness of the estimation technique(s) applied and key assumptions, including treatment of extreme grade values, domaining, interpolation parameters and maximum distance of extrapolation from data points. If a computer assisted estimation method was chosen include a description of computer software and parameters used. A mineralised envelope is created encompassing all zones of significant mineralisation. A number of different domains have been interpreted based on a broad
mineralisation envelope at a nominal cut-off of 40ppm U3O8.Geostatistical variogram modelling was used to determine appropriate parameters for estimation of uranium grade
using Ordinary Kriging (OK) (for all Domains) followed by the application of Uniform Conditioning (UC) and Local Uniform Conditioning (LUC) using Isatis Software, in
order to simulate the grade tonnage distribution based on a Selective Mining Unit (SMU) of 5m x 5m x 6m for all Domains..Surpac software was used for mineralisation
volume interpretation and Isatis for uranium grade estimation.Four sources of drillhole uranium grade data was used, the proportions of data within the mineralised volume
by length are:· Chemical U3O8 (ppm): 56.3%· Radiometric Equivalent (ppm): 30.6%· Portable XRF (ppm): 0.8%· Background waste values based on XRF and Gamma
probe results (10ppm U3O8): 12.3%A number of holes which were used to determine the mineralisation volume were excluded from the grade estimation process. These consisted
of 32 JEN holes where the radiometric equivalent value indicated mineralisation but the eU3O8 value was composited over the entire mineralisation length, resulting in
these holes being unsuitable for local grade estimation.The drill hole spacing is nominally 50m by 50m, with infill spacing at 35m by 35m within the Measured Resource
areas and part of the Indicated Resource.Eight mineralisation domains were identified at Retortillo (R2, R3, R4, R5, R6, R7, S1 and S2). 1m samples composites were used
to estimate grade into 20m by 20m by 6m parent blocks with 5m by 5m by 6m blocks used for UC selectivity conditioning.In order to reduce local bias due to extreme high
grades, top cuts were applied: · R2: 1,100ppmU3O8· R3: 1,800ppmU3O8· R4: not applied· R5: 3,800ppmU3O8· R6: 2,000ppmU3O8· R7: not applied·
S1: 2,500ppmU3O8· S2: 2,500ppmU3O8Appropriate search volumes, minimum and maximum sample numbers and top cutting strategy were used based on the results of
Kriging Neighbourhood Analysis.The variogram nugget % and maximum ranges in the order of major, semi-major and minorper domain in meters are presented below:· R2:
31%/74/72/55· R3: 18%/105/90/23· R4: 36%/44/31/25 taken from R5 as insufficient data· R5: 36%/44/31/25· R6: 32%/79/50/109· R7: 32%/79/50/109
taken from R6 as insufficient data· S1: 31%/65/85/38· S2: 30%/128/85/27In-situ dry bulk densities were assigned based on zones of weathering intensity and used
to estimate tonnage.
The availability of check estimates, previous estimates and/or mine production records and whether the Mineral Resource estimate takes appropriate account of such data. The current resource estimate was compared with the previous resource estimate (April 2015) which was based on a more constrained mineralisation envelope and Ordinary
Kriging grade estimation with no adjustment for mining selectivity. The updated MRE has 4% less tonnes with a 15% higher grade for a 7% increase in metal. This increase
in grade and metal was anticipated as a result of modelling the mineralisation using increased selectivity at the 200 ppm grade cut-off.No mining production has taken
place at Retortillo.
The assumptions made regarding recovery of by-products. The resource model only estimates uranium.
Estimation of deleterious elements or other non-grade variables of economic significance (eg sulphur for acid mine drainage characterisation). At this stage, there are no deleterious elements or other non-grade variables identified as being of economic significance at Retortillo.
In the case of block model interpolation, the block size in relation to the average sample spacing and the search employed. The uranium grade is estimated into the 20m (X) by 20m (Y) by 6m (Z) blocks. This compares to the average drill spacing of 35m by 35m in X and Y and an assumed mining
bench height of 6m. UC and LUC were applied to the model based on PFS designed mining selectivity at a block size of 5m x 5m x 6m.
Any assumptions behind modelling of selective mining units. Selective mining unit dimensions are based on using a blasting and sampling pattern which is around 5m x 5m combined with open pit mining equipment suitable for
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