REG - Thor Mining PLC - Kapunda Copper Resources - ASX clarification <Origin Href="QuoteRef">THRL.L</Origin> - Part 3
22/02/2018 10:37
- Part 3: For the preceding part double click ID:nRSV6523Fb
checked with the digital datasets from Stuart Metals and Copper Range.
Where differences were found between the data contained in the original
company reports and the provided Stuart Metals database, the original
companies' values were used.
The data was then imported into a
Maxwell Geo Services' DataShed and QAQCR were used to validate the data viz;
overlapping intervals, excessive drillhole deviation, assay QAQC. Secondary
validation by Maptek's Vulcan software and visual validation.
Site visits · Comment on any site visits undertaken by the Competent Person and The Competent Person has undertaken several site visits to the Kapunda
the outcome of those visits. project. These visits have verified that the dimensions of the physical site
correspond with dimensions implied by the data sets. Copper oxide in the form
of malachite is present in the mullock piles and copper efflorescence visible
on many of the historic pit faces. Evidence of previous mining operations is
visible with numerous open cuts, shafts and waste dumps still clearly visible.
Visits have also been undertaken at the South Australian Drill Core Reference
Library where over 100 Kapunda drillholes are stored.
· If no site visits have been undertaken indicate why this is the Site visits have been undertaken.
case.
Geological interpretation · Confidence in (or conversely, the uncertainty of) the geological The extensive surface and underground mining of the Kapunda lodes combined
interpretation of the mineral deposit. with the large amount of diamond drilling history of the Kapunda projects
implies confidence in the current geological interpretation There are no
alternative geological models of the secondary copper mineralisation (copper
oxides and secondary copper sulphides).
The vertical extent of secondary copper mineralisation modelled by Terramin
using drillhole data is broadly comparable to the line "approximate lower
limit of secondary enrichment" mapped out on a longitudinal section produced
by the South Australian Mines Department in 1942 (Plan N2788).
· Nature of the data used and of any assumptions made. The 2018 Kapunda Resource utilized data from 78 diamond and 109 percussion
holes with a combined meterage of 22,712.8m.
Original lab assays were used.
Resampling and lab analysis of selected diamond core intervals and xrf
analysis of drill chips from percussion holes stored at the South Australian
Drill Core Reference Library by both Copper Range Pty and Terramin confirmed
the appropriateness and accuracy of historic assay methods.
All original density measurements were considered inappropriate as they did
not make allowances for porosity of the rock. ECR and Terramin collected 202
new density measurements from 19 drillholes using a modified Archimedes
method. Historically the assumed density was between 2.0 t/m(3) (ACC and
Stuart Minerals) and 2.4 t/m(3) (BHS and Northland) whereas the average
calculated density of the 2018 Mineral Resource estimate is only 1.84 t/m(3).
· The effect, if any, of alternative interpretations on Mineral No alternative interpretations for the secondary copper enrichment have been
Resource estimation. put forward for serious consideration. Alternative geological interpretations
may be developed with further drilling but in the Competent Person's opinion
they would not significantly affect the global resource estimate, but could
affect local estimates.
· The use of geology in guiding and controlling Mineral Resource The 2018 Mineral Resource estimate was focused on defining the extent and
estimation. nature of secondary (oxide/supergene) copper mineralisation. Important
boundaries modelled were the top and base of copper oxides, top and base of
secondary sulphides and top of primary copper sulphides.
The lower limit of (significant) weathering corresponds with the base of
secondary copper mineralisation.
Detailed geological control has not been attempted at this stage. Primary
copper mineralisation was bounded on the east by the Mine Fault, which dips
65°E. The old workings immediately west of this structure occur principally
in sets of en echelon lodes comprising of quartz-sulphide filled fractures of
which 28 were worked at an average width of 45cm.
· The factors affecting continuity both of grade and geology. The main controlling features of the secondary copper are seen to be proximity
to primary mineralisation, the water table and the partial replacement of
pyritic horizons by copper within the supergene zone and depth of weathering.
Dimensions · The extent and variability of the Mineral Resource expressed as The Mineral Resource has a strike length of 1700m, a plan width of 500m and
length (along strike or otherwise), plan width, and depth below surface to the has been limited to a maximum depth of 100m. Copper mineralisation was
upper and lower limits of the Mineral Resource. historically mined from surface and copper efflorescence is visible on many of
the pit faces.
Estimation and modelling techniques · The nature and appropriateness of the estimation technique(s) Wireframes modelled included; top and base of copper oxide mineralisation, top
applied and key assumptions, including treatment of extreme grade values, and base of secondary copper sulphides and top of primary copper sulphides.
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.
Compositing of drillhole samples was completed at 2m (downhole) intervals,
with composites flagged to identify the copper's mineralogy.
The 2m composites were used for statistical analysis and continuity modeling.
Variogram models for copper were developed using Snowden's Supervisor
software.
Ordinary kriging estimation technique was used for estimation of copper grade.
Estimation of blocks was limited to a maximum of three composites per hole
from a maximum of three drillholes.
Maximum distance of extrapolation was limited to 100m.
There are no "extreme grade values" as all copper grades of the 2m composites
were below the average historic production grade of 19% copper. The maximum
assay from the oxide and secondary sulphide portions of the Resource estimate
were respectively 6.3% and 17.7% copper.
All geological modelling, block model construction, grade interpolation and
reporting were completed using Maptek's Vulcan software.
· The availability of check estimates, previous estimates and/or Previous Mineral Resource estimates, calculated for mining by open cut are;
mine production records and whether the Mineral Resource estimate takes
appropriate account of such data. · BHS (1969) - 5.5Mt @ 0.74% copper for 41,000t of contained metal.
· Northland (1978) - 6.3Mt @ 1.50% copper for 94,000t of contained
metal.
· ACC (1989) - 7.2 Mt @ 0.83% copper for 60,000 tonnes of
contained metal
· Stuart Metals (1992) - 4.3 Mt @ 1.10% copper for 47,000 tonnes of
contained metal.
·
· The assumptions made regarding recovery of by-products. No assumptions made. Potential by-products have not been modelled.
· Estimation of deleterious elements or other non-grade variables No deleterious elements have been estimated. For the majority of drillholes
of economic significance (eg sulphur for acid mine drainage characterisation). only copper was analysed.
· In the case of block model interpolation, the block size in The parent block size is 25 m E by 25 mN by 5.0 m RL. Sub blocking of 1mE by
relation to the average sample spacing and the search employed. 1mN by 1mRL was required to honour wireframe boundaries of the historic
underground workings. Sub blocks used parent block's grade.
Drilling is typically on 50m spaced sections with drillholes on sections
variably spaced 10m to 60m.
· Any assumptions behind modelling of selective mining units. The selective mining unit reflects ISR as the proposed extractive technique.
· Any assumptions about correlation between variables. No correlation between variables assumptions is made.
· Description of how the geological interpretation was used to Geological logs were used to map out the extents of copper oxides, secondary
control the resource estimates. and primary copper sulphides which were validated against Hylogger results and
core inspections undertaken by Terramin.
Surfaces generated included; base of copper oxides, top and base of secondary
copper sulphides and top of primary copper sulphides.
Estimation and modelling techniques (continued) · Discussion of basis for using or not using grade cutting or No top cuts were applied. This was considered appropriate as all copper grades
capping. of the 2m composites were below the average historic production grade of 19%
copper. The maximum assay from the oxide and secondary sulphide portions of
the Resource were respectively 6.3% and 17.7% copper.
· The process of validation, the checking process used, the Various visual and statistical checks were undertaken to validate modelling
comparison of model data to drill hole data, and use of reconciliation data if and grade interpolation. The global results are comparable with the reported
available. OK models with localised differences as expected.
Moisture · Whether the tonnages are estimated on a dry basis or with natural The Mineral Resource estimate is based upon dry tonnages. Moisture content has
moisture, and the method of determination of the moisture content. not been included.
Cut-off parameters · The basis of the adopted cut-off grade(s) or quality parameters A cut-off of 0.05% total copper for oxide and transitional is industry
applied. standard for ISR of copper projects.
Both Excelsior Mining Corp and Cirus Resources Ltd both use a resource cut-off
of 0.05% copper in their economic studies for their respective Gunnison Copper
Project and Florence Copper Project located in Arizona, USA.
Mining factors or assumptions · Assumptions made regarding possible mining methods, minimum The proposed use of the ISR method to extract copper from oxide and secondary
mining dimensions and internal (or, if applicable, external) mining dilution. sulphide copper mineralization was chosen based on several criteria including:
It is always necessary as part of the process of determining reasonable the majority of the ore body sitting below the water table; the fractured
prospects for eventual economic extraction to consider potential mining nature of the host rock providing transmissivity for fluids through the
methods, but the assumptions made regarding mining methods and parameters when preferentially mineralized fracture systems; the potential amenability of the
estimating Mineral Resources may not always be rigorous. Where this is the mineral species to the leaching and recovery process; the relatively low
case, this should be reported with an explanation of the basis of the mining visual and environmental impact of the ISR method (no bulk movement of rock,
assumptions made. no open cut pits or waste dumps, little noise or dust pollution) given the
proximity of the orebody to the local population.
Metallurgical factors or assumptions · The basis for assumptions or predictions regarding metallurgical While historic work has shown the mineral species to be targeted are amenable
amenability. It is always necessary as part of the process of determining to leaching by a number of lixiviant systems, detailed metallurgical test work
reasonable prospects for eventual economic extraction to consider potential has not been completed at this stage.
metallurgical methods, but the assumptions regarding metallurgical treatment
processes and parameters made when reporting Mineral Resources may not always
be rigorous. Where this is the case, this should be reported with an
explanation of the basis of the metallurgical assumptions made.
Environmental factors or assumptions · Assumptions made regarding possible waste and process residue ISR allows the extraction of minerals with little physical disturbance to the
disposal options. It is always necessary as part of the process of determining environment. Since there is no physical movement of rock, there are no open
reasonable prospects for eventual economic extraction to consider the cut pits, shafts or dumps to manage on surface. ISR is a closed loop system
potential environmental impacts of the mining and processing operation. While that generates much smaller volumes of mining and hydrometallurgical effluents
at this stage the determination of potential environmental impacts, that require management than conventional operations. While little current
particularly for a greenfields project, may not always be well advanced, the environmental work has been carried out on the project to date, it is assumed
status of early consideration of these potential environmental impacts should that waste will be minimal and will be disposed of at an EPA licenced
be reported. Where these aspects have not been considered this should be facility.
reported with an explanation of the environmental assumptions made.
Bulk density · Whether assumed or determined. If assumed, the basis for the Historic density measurements were considered inappropriate as they did not
assumptions. If determined, the method used, whether wet or dry, the frequency make allowances for porosity of the rock.
of the measurements, the nature, size and representativeness of the samples.
ECR and Terramin collected 202 new density measurements from 19 drillholes
using a modified Archimedes method.
Previous Resource estimates used an averaged density. was between and BHS and
Northland used a density of 2.4 t/m(3) and ACC and Stuart Minerals 2.0
t/m(3). While the average interpolated density for the 2018 Mineral Resource
estimate is 1.84 t/m(3).
· The bulk density for bulk material must have been measured by The modified Archimedes method is considered an appropriate method as it
methods that adequately account for void spaces (vugs, porosity, etc), allows for water absorption, there was no slaking of the samples and no vugs
moisture and differences between rock and alteration zones within the deposit. were present.
· Discuss assumptions for bulk density estimates used in the Bulk density was modelled using the same domains and search parameters used
evaluation process of the different materials. for the copper mineralisation.
There is slight negative correlation with copper grade, presumed due to
increased kaolinization of the metasediments..
Classification · The basis for the classification of the Mineral Resources into The whole Kapunda Mineral Resource has been classified as Inferred.
varying confidence categories.
It is the view of the Competent Person that additional hydrological studies
and leaching tests are required before any portion of the Mineral Resource can
be classified at a higher confidence category than Inferred.
· Whether appropriate account has been taken of all relevant Historic data input is well documented and considered reliable.
factors (ie relative confidence in tonnage/grade estimations, reliability of
input data, confidence in continuity of geology and metal values, quality, Within the Resource the distribution of data and continuity is good.
quantity and distribution of the data).
· Whether the result appropriately reflects the Competent Person's The result appropriately reflects the Competent Person's view of the deposit.
view of the deposit.
Audits or reviews · The results of any audits or reviews of Mineral Resource The 2018 Mineral Resource Estimate has been reviewed Terramin Australia.
estimates.
Discussion of relative accuracy/ confidence · Where appropriate a statement of the relative accuracy and This Kapunda Mineral Resource estimate relates to copper oxide and secondary
confidence level in the Mineral Resource estimate using an approach or copper sulphide mineralisation within 100m of surface.
procedure deemed appropriate by the Competent Person. For example, the
application of statistical or geostatistical procedures to quantify the
relative accuracy of the resource within stated confidence limits, or, if such
an approach is not deemed appropriate, a qualitative discussion of the factors The Mineral Resource estimate is considered robust and representative. This
that could affect the relative accuracy and confidence of the estimate. model is intended only for use in aiding scoping study investigations into the
use if ISR.
The Mineral Resource estimate has been classified in accordance with the JORC
Code, 2012 Edition using a qualitative approach. All factors that have been
considered have been sufficiently documented in Section 1 and Section 3 of
this Table.
· The statement should specify whether it relates to global or The Kapunda Mineral Resource estimate relates to the copper oxide and
local estimates, and, if local, state the relevant tonnages, which should be secondary copper sulphide mineralisation where it is likely to have local
relevant to technical and economic evaluation. Documentation should include variability. The global assessment is more of a reflection of the average
assumptions made and the procedures used. tonnes and grade estimate.
· These statements of relative accuracy and confidence of the Historic production data is not relevant for the proposed ISR extraction
estimate should be compared with production data, where available. method as the ISR method will target the low grade halo to the historically
mined mineralisation.
Mining of the high grade supergene from 1844 to 1866, largely from underground
produced 13,500t of copper from 68,000t of ore at an average grade of 19.8%
copper. From 1867 to 1878 approximately 300,000t of tailings, waste rock and
low grade copper mineralisation mined from open cuts were leached to produce
1,600t of copper at an average grade of 0.5%.
This information is provided by RNS
The company news service from the London Stock Exchange
Sample sizes are considered appropriate.
Quality of assay data and laboratory tests · The nature, quality and appropriateness of the assaying and laboratory procedures used and whether the technique is considered partial or total. Assaying was carried out at certified analytical laboratories and the techniques are considered appropriate, although little historical information is available on checks
and standards. Mines Exploration KP holes and Northland's K series were analysed by Amdel Analytical Services (Amdel) for copper using their F1 scheme, an A.A.S. method.
Amdel claimed a +/-5% accuracy. KD series drillholes were assayed by Labtech Pty. Ltd. - 101B for copper using a hot, long perchloric acid digestion, AAS determination.
No information is available on checks and standards. Utah's KP series rotary percussion drillholes were analysed at Labtech Pty Ltd. Midland W.A. using a hot long
perchloric acid digestion with AAS determination for copper No information is available on checks and standards.
· For geophysical tools, spectrometers, handheld XRF instruments, etc, the parameters used in determining the analysis including instrument make and model, reading times, calibrations factors applied and their derivation, etc. Geophysical tools, spectrometers, handheld XRF instruments, etc. were not available to earlier companies.Terramin utilised hand held XRF analyses to validate copper assays from selected percussion holes stored at the South Australian Drill Core Reference Library and as an aid to geological interpretation. No geophysical tools were used by Terramin to estimate published mineral or element percentages.
· Nature of quality control procedures adopted (eg standards, blanks, duplicates, external laboratory checks) and whether acceptable levels of accuracy (ie lack of bias) and precision have been established. Minimal historical information is available on the use of standards, blanks or duplicates. The use of check analyses were documented by Northland. Check analyses were undertaken at their main laboratory, Amdel and cross lab checks done at Robertson Research and McPhar Geophysics. Original assay reports from Amdel show that at the time they ran a mix of standards and blanks every fifteenth sample, although the results of these internal lab checks were not documented.
Verification of sampling and assaying · The verification of significant intersections by either independent or alternative company personnel. Utah's KD005 which returned from 45m, 27m @ 1.18% copper was resampled by Copper Range in 2007. Copper Range's resampling returned from 45m, 27m @ 1.20% copper. Utah's
deep intercept of primary copper sulphide in KD011 returned from 426m, 11m @ 2.00% copper was resampled by Terramin returned from 426m, 11m @ 1.89% copper and 0.1g/t
gold. Terramin's samples were a quarter cut of the remaining half core sample. (TZN ASX announcement - 1st Quarter Report, 29/4/2016) Other significant intersections from
drill core have been visually reviewed by Terramin and ECR staff. Terramin has also utilised a hand held XRF to validate copper assays of percussion holes stored at the
South Australian Drill Core Reference Library.
· The use of twinned holes. There were two sets of planned twin holes: KD001 twinned drillhole K015 and KD0019 twinned drillholes KP046 and K076. There are a further 6 pairs of drillholes that are close enough to be considered twins. As part of compiling data for the Kapunda Mineral Resource estimate it was deemed necessary to be comfortable with the wide variety of drilling and sampling methods used on the Kapunda Project over a number of years.In order to look at the issue it was decided to; · Compare summary statistics for the different drillhole series.· Compare a selection of twined holes.· Compare poor recovery core holes with good recovery drillholes · Compare rotary drilling with diamond drilling within a specific, geologically constrained spatial area.· The process entailed creating a 2m downhole composite set of drill assays and splitting these into their component drill series types for statistical analysis.Results;· The results in general show no significant bias due to drilling type.· Twin holes Q-Q plots indicate there is little bias.· There appears to be very little difference between holes with poor core recovery versus those with good core recovery.· While there are some individual difference between rotary and diamond holes, looking at a larger sample they appear to give relatively consistent results.
· Documentation of primary data, data entry procedures, data verification, data storage (physical and electronic) protocols. Primary data was recorded on paper log sheets, photocopies of originals were submitted as part of statutory reporting. These have subsequently been scanned to PDF and made available online at South Australian Resources and Information Gateway (SARIG)in the Resource and Energy Georeference Database. Terramin was also able to obtain digital data sets of the drill data from Copper Range Ltd and the digital data set used by Stuart Metals NL (Stuart Metals) for their 1992 Kapunda Resource estimate. Where differences were found between the data contained in the original company reports and the data provided by Stuart Metals database, the original companies' values were used. The data was entered into Excel spreadsheets before being imported into a Maxwell Geo Services' DataShed and QAQCR which was used to validate the data viz; overlapping intervals, excessive drillhole deviation, assay QAQC. Secondary validation by Maptek's Vulcan software and visual validation was also undertaken.
· Discuss any adjustment to assay data. No adjustments are made to reported summary intersections. The Mineral Resource estimate makes an allowance for core loss with lost intervals assumed to have a zero grade.
Location of data points · Accuracy and quality of surveys used to locate drill holes (collar and down-hole surveys), trenches, mine workings and other locations used in Mineral Resource estimation. Mines Exploration established the original grid baseline parallel to main strike of mineralization with grid north at 335 degrees magnetic. All subsequent companies,
except for Copper Range used this grid. Initial survey control was by licensed surveyor using theodolite. Collars were fixed by theodolite surveys and metal pin bench
marks. Coordinate position 1000N 00E (collar of drillhole KV002). The majority of drill collar locations were recorded in company reports and in Stuart Metals digital
database. A few remaining drillhole collar locations were obtained from georeferenced maps. Originally drillhole collar RL's were calculated relative to drillhole KV002
but Northland in 1972 had the site resurveyed relative to the State Datum. To allow for the incorporation of drillhole data from Copper Range an affine transformation was
used to convert the earlier drillhole coordinates to MGA Zone 54 (GDA 94).
· Specification of the grid system used. The data is reported in grid system MGA Zone 54 (GDA94).
· Quality and adequacy of topographic control. In 1972 Northland Minerals contracted surveying consultants Alex & Symonds Pty Ltd to survey the site and locate drill collars. The level datum used throughout the grid and drillhole levelling is based upon a Lands Department Bench Mark Number 6921. A digital terrain model was created by Terramin from the survey's 528 survey points collected across the deposit. Drillhole collar RL's not picked up during this survey were then assigned a value from this surface.With the exception of the historic workings, the area has low relief. The site has a gentle slope to the south, over the 1,500m of strike length there is just a maximum difference of 25m in collar RLs.
Data spacing and distribution · Data spacing for reporting of Exploration Results. Drillhole spacings and sample interval lengths are considered appropriate.
· Whether the data spacing and distribution is sufficient to establish the degree of geological and grade continuity appropriate for the Mineral Resource and Ore Reserve estimation procedure(s) and classifications applied.
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