REG - Castillo Copper Ltd - Preliminary test-work findings
14/06/2023 07:00
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RNS Number : 6193C Castillo Copper Limited 14 June 2023
14 June 2023
CASTILLO COPPER LIMITED
("Castillo", or the "Company")
Preliminary test-work findings; progress with copper assets
Castillo Copper Limited (LSE and ASX: CCZ), a base metal explorer primarily
focused on copper across Australia and Zambia, is pleased to announce that it
has received specialist consultant, ANSTO's(1), preliminary report on
metallurgical test-work undertaken on six samples from the Fence Gossan,
Reefs, and Tors Tanks Prospects (BHA Project's East Zone).
HIGHLIGHTS:
· Specialist consultant, ANSTO(1), performed metallurgical test-work on
six samples from the Fence Gossan, Reefs, and Tors Tanks Prospects (BHA
Project's East Zone) which produced the following preliminary findings:
o The Total Rare Earth Element ("REE") plus Yttrium ("TREY") grades for the
six samples ranged from 227 to 1,632 ppm TREY;
o The proportion of high-value Magnetic Rare Earth Oxides (MREO;
Nd+Pr+Dy+Tb) to Total REO ("TREO") across the six samples ranged from 22% to
27%; and
o The best TREY extraction, using a direct leach process at pH 1, was 30%.
· The Board is reviewing next steps, including trialing alternate leach
tests proposed by ANSTO(1) to improve extraction results
· Entech Mining(2) are finishing the pit optimisation and mine design
study for the Big One Deposit (MRE: 2.1Mt @ 1.1% Cu for 21,886t2 copper metal
- inferred)(3)
· Castillo's geology team are close to completing an update on the 2017
Mineral Resource Estimate ("MRE") for Cangai Copper Mine(4) which will factor
in results from drilling campaigns post 2017
Ged Hall, Chairman of Castillo Copper, said: "The Board is pleased the work by
ANSTO ratified the earlier assay results and high MREO to TREO ratio. However,
the Board is now reviewing ANSTO's recommendations on how to improve the
metallurgical results from the BHA Project's East Zone. The Board's focus is
now on the Australian copper assets, with critical reports due on Cangai
Copper Mine and Big One Deposit that could aid materially in securing
development partners."
METALLURGICAL TEST-WORK FINDINGS
The metallurgical test work delivered the following findings:
· The TREY grades for the six samples ranged from 227 to 1,632 ppm TREY
which is consistent with earlier assay results; and
· The proportion of high-value MREO (Nd+Pr+Dy+Tb) to TREO across the
six samples ranged from 22% to 27% and aligns with earlier calculations
(Figure 1).
FIGURE 1: RARE EARTH ELEMENT COMPOSITION OF HEAD SAMPLES (PPM)
Elements TT-002RC TT-005DD FG-003RC FG-004RC RT-001RC RT-001RC A
La 199 283 335 215 47 206
Ce 450 423 488 411 90 410
Pr 49 75 62 47 10 47
Nd 203 316 220 174 37 174
Sm 43 67 36 32 7 29
Eu 10 16 6 5 1 2
Gd 44 66 28 21 5 18
Tb 7 10 4 3 1 1
Dy 37 53 20 17 4 3
Ho 7 9 3 3 1 0
Er 18 26 10 8 2 0
Tm 2 3 1 1 0 0
Yb 14 21 8 7 2 0
Lu 2 3 1 1 0 0
Y 169 261 88 71 20 7
LREE 901 1097 1105 847 184 837
HREE 185 274 117 96 23 53
Magnets 296 454 305 241 52 226
TRE+Y 1254 1632 1309 1014 227 897
MREO 347 532 358 282 61 265
TREYO 1509 1958 1570 1218 273 1076
MREO/TREO (%) 23.0 27.1 22.8 23.2 22.7 24.7
LRE = La, Ce, Pr, Nd; HRE = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; Magnets
= Pr, Nd, Tb, Dy; MREO = magnet oxides (Note, under ANSTO's definition MREO
comprises 4 elements, not six (Gd and Sm not counted); TREO = Total oxides
Source: ANSTO
For the metallurgy, all tests were calculated using the solid head and the
leach liquor analysis. The best TREY extraction, using a direct leach process
at pH 1, was 30% (Figure 2).
To potentially improve on these results, the Board is reviewing
recommendations put forward by ANSTO which includes:
· Assess a wider variety of samples to validate the leach results
across the East Zone; and
· Consider additional leach tests using hydrochloric acid to assess
whether increased REE dissolution can be achieved using an alternative
lixiviant for an increased leach duration time.
FIGURE 2: SUMMARY OF LEACH EXTRACTIONS (0.5 M (NH4)2SO4 SOLUTION)
Sample ID TT-002RC TT-005DD FG003RC FG-004RC RT-001RC RT-001RC A
Head TREY (ppm) 1254 1632 1309 1014 227 897
Test ID CCZ-1 CCZ-7 CCZ-2 CCZ-8 CCZ-3 CCZ-9 CCZ-4 CCZ-10 CCZ-5 CCZ-11 CCZ-6 CCZ-12
pH 4 1 4 1 4 1 4 1 4 1 4 1
Duration (h) 0.5 2 0.5 2 0.5 2 0.5 2 0.5 2 0.5 2
Extraction (%)
La 1 2 1 2 1 3 2 4 11 33 2 3
Ce 1 2 1 3 1 3 2 5 11 33 2 4
Pr 1 2 1 2 1 3 2 5 12 32 2 3
Nd 1 3 1 3 1 3 2 6 11 36 2 4
Sm 1 4 1 3 1 4 3 6 10 32 2 5
Eu 4 2 3 4 5 5 20 39 12
Gd 1 9 1 4 2 7 2 6 9 33 1 5
Tb 10 2 5 6 7 35
Dy 1 17 2 4 2 12 3 5 6 17 7
Ho 20 3 5 13 8
Er 1 26 2 5 2 16 3 6 11
Tm 29 7 19
Yb 2 29 2 7 3 17 4 4
Lu 33 7 18
Y 2 27 2 5 3 18 2 5 5 11 4 14
LRE 1 2 1 3 1 3 2 5 11 34 2 4
HRE 1 13 2 4 2 8 3 6 7 24 1 5
Magnets 1 5 1 3 1 4 2 6 11 34 2 4
TREY 1 7 1 3 1 5 2 5 10 31 2 4
TREY-Ce 1 10 1 3 1 6 2 5 9 29 2 4
Test methodology
A diagnostic desorption test was completed on each sample under the following
conditions:
· 0.5 M (NH(4))2SO(4) as lixiviant;
· pH 4;
· 0.5 h;
· Ambient temperature (~22 (O)C); and
· 4 wt% solids density.
All diagnostic leach tests were carried out on pulverised samples (80 g) at
high L/S ratio, where there are no effects of adsorption and co-precipitation.
These tests indicate the maximum extraction that could be achieved under ideal
test conditions (at more practical lower L/S ratios, extraction could be
less). Where required, 1 M H2SO4 was added to maintain the pH at 4 throughout
the test duration.
At the completion of the test, the slurry was filtered to separate the leach
liquor (PF) and the leached residue. The PF was analysed by ICP-OES at ANSTO
for gangue elements, and at ALS Brisbane by ICP-MS for the REs and Sc, Th and
U. The residue was washed on the filter with DI water (200 mL), dried and
weighed. The water wash and residues were retained but not analysed.
A diagnostic leach test was conducted on each pulverised sample under the
following acid leach conditions:
· 0.5 M (NH(4))2SO(4) as lixiviant;
· pH 1;
· 2 h;
· 50 (O)C; and
· 4 wt% solids density.
The test procedure was like the foregoing method, throughout the 2h test, the
pH was maintained at pH 1 where necessary by addition of concentrated H2SO4.
No intermediate thief samples were taken.
At the completion of the test, the slurry was filtered to separate the PF and
the leached residue. The PF was analysed by ICP-OES at ANSTO for gangue
elements, and at ALS by ICP-MS for the REs and Sc, Th and U. The residue was
washed on the filter with DI water (200 mL), dried and weighed. The residues
were analysed by XRF at ANSTO for major gangue elements and by lithium
tetraborate fusion digest/ICPMS at ALS for the REs, Sc, Th and U. The wash was
retained but not analysed.
For further information, please contact:
Castillo Copper Limited +61 8 6558 0886
Dr Dennis Jensen (Australia), Managing Director
Gerrard Hall (UK), Chairman
SI Capital Limited (Financial Adviser and Corporate Broker) +44 (0)1483 413500
Nick Emerson
Gracechurch Group (Financial PR) +44 (0)20 4582 3500
Harry Chathli, Alexis Gore, Henry Gamble
About Castillo Copper
Castillo Copper Limited is an Australian-based explorer primarily focused on
copper across Australia and Zambia. The group is embarking on a strategic
transformation to morph into a mid-tier copper group underpinned by its core
projects:
· A large footprint in the Mt Isa copper-belt district, north-west
Queensland, which delivers significant exploration upside through having
several high-grade targets and a sizeable untested anomaly within its
boundaries in a copper-rich region.
· Four high-quality prospective assets across Zambia's copper-belt
which is the second largest copper producer in Africa.
· A large tenure footprint proximal to Broken Hill's world-class
deposit that is prospective for zinc-silver-lead-copper-gold and platinoids.
· Cangai Copper Mine in northern New South Wales, which is one of
Australia's highest grading historic copper mines.
The group is listed on the LSE and ASX under the ticker "CCZ."
Competent Person's Statement
The information in this report that relates to Exploration Results for "BHA
Project, East Zone" is based on information compiled or reviewed by Mr Mark
Biggs. Mr Biggs is a director of ROM Resources, a company which is a
shareholder of Castillo Copper Limited. ROM Resources provides ad hoc
geological consultancy services to Castillo Copper Limited. Mr Biggs is a
member of the Australian Institute of Mining and Metallurgy (member #107188)
and has sufficient experience of relevance to the styles of mineralisation and
types of deposits under consideration, and to the activities undertaken, to
qualify as a Competent Person as defined in the 2012 Edition of the Joint Ore
Reserves Committee (JORC) Australasian Code for Reporting of Exploration
Results, and Mineral Resources. Mr Biggs holds an AusIMM Online Course
Certificate in 2012 JORC Code Reporting. Further, Mr Biggs consents to the
inclusion in this report of the matters based on information in the form and
context in which it appears.
References
1) ANSTO. Available at:
https://www.ansto.gov.au/services/resources-sector/minerals
2) Entech Mining. Available at:
https://entechmining.com.au
3) CCZ ASX Release - 28 February 2022 & 20 February
2023
4) CCZ ASX Release - 28 September 2018 (Annual Report
2018), 3 September 2018, 19 February 2020, 28 April 2020 & 9 March 2023
APPENDIX A: BHA PROJECT'S EAST ZONE
FIGURE A1: BHA PROJECT's EAST ZONE - REE EXPLORATION FOOTPRINT
Source: CCZ geology team
FIGURE A2: BHA PROJECT
Source: CCZ geology team
APPENDIX B: ANSTO METALLURGICAL TESTING
Castillo identified clay-hosted REE mineralisation at its Fence Gossan, Tors
and Reefs Tanks Prospects(1), which are within the BHA Project's East Zone,
located about 30km from Broken Hill.
Initial flotation tests showed REE minerals can be separated from the clays by
flotation to produce a higher-grade concentrate (2-3 times REE enrichment).
Castillo wants to develop an understanding of the potential to extract the
REEs contained in the clay zones.
Castillo contacted(2) ANSTO and requested a work program to characterise the
REE/clay mineralisation with respect to RE leachability for six samples
ranging from fresh pegmatite to highly weathered clay (see Figure B1). The
MREO grades of the samples to be supplied vary from 362 ‑ 603 ppm.
(1) ASX Announcements 23(rd) November 2022, and 16(th) and 28(th) February
2023.
(2) Phone call from Mark Biggs (ROM Resources, 24(th) February 2023).
FIGURE B1 SAMPLE DESCRIPTIONS
Drillhole Sample Number(s) From (m) To (m) Thick. (m) Comments*
TT_002RC CCZ03888-92 14.00 19.00 5.00 MREO = 466 ppm; highly weathered clay
TT_005DD CCZ04936-49 5.00 18.00 13.00 MREO = 603 ppm; highly weathered clay
FG_003RC CCZ04513-30 2.00 20.00 18.00 MREO = 459 ppm; Also, Preliminary Met ALS Perth sample; highly weathered clay
FG_004RC CCZ04686-91 7.00 13.00 6.00 MREO = 427 ppm; highly weathered clay
RT_001RC CCZ03819-21 14.00 17.00 3.00 MREO = 466 ppm; highly weathered clay
RT_001RC CCZ04869 64.00 65.00 1.00 MREO = 362 ppm; fresh pegmatite
*MREO = Magnetic REEs (ANSTO definition: Pr, Nd, Tb, Dy)
Source: ANSTO
A key early question for Castillo is to establish the proportion of ionically
adsorbed REEs, and the potential for increased extraction of the REEs by a
simple direct acid leaching approach.
Clay rare earth deposits
The so-called REE ionic clay deposits (IAD) are commercially leached in China
and Myanmar as a major source of heavy REE. A feature of the IADs is the
REEs are present as physically adsorbed ions which can be readily solubilised
by displacing the REE ions with an appropriate cation. Typical desorption
conditions are contact with 0.3-0.5 ammonium sulfate (AS) at pH 4-5 for ~ 30
minutes at ambient temperature, 20-30 wt% solids. Under these conditions up
to 70% extraction (typically 40-60%) of TRE+Y can be obtained, with very
little dissolution of gangue elements, which makes for simple downstream
processing to produce a mixed REE carbonate.
Over the last few years, there have been numerous reports of elevated
concentrations of REEs associated with clays, but in most cases the deposits
have not proven to be of the classic ionic clay type, and a lower pH has been
found to be necessary to dissolve the REE's. Under these circumstances, the
economics of the process will depend on RE extraction, acid consumption and
the concentrations of dissolved gangue elements.
An initial indication of potential economic viability can be obtained by
leaching under desorption conditions (pH 4) and a lower pH to determine REE
extraction(3) versus gangue dissolution.
(3) Total REE extraction is not necessarily the best indicator as the
individual REs will likely dissolve to different extents, and the value of the
individual REs varies significantly (the most valuable are Nd, Pr, Tb, Dy).
Objectives and scope
The main objective of the work program is to assess the leachability of REEs
from clay samples over a range of pHs.
The specific tasks in the scope were:
o Drying of as-received samples and preparation for compositing, assay and
leach tests.
o Head assays on six samples (XRF, fusion digest/MS).
o Carry out a diagnostic leach on the 6 samples using ammonium sulfate (AS)
at pH 4.
o Carry out a diagnostic leach tests on 6 samples using ammonium sulfate at
pH 1 (in sulfuric acid).
o Provision of a data pack, with a summary note and discussion of the main
findings.
Chondrite plot
A method for providing confidence in the accuracy of the analysis of samples
containing REEs is to produce a Chondrite plot. Normalisation against
Chondrite meteorite concentrations removes the normal 'saw tooth' distribution
obtained from the concentration profile and readily highlights differences in
the relative concentrations of individual REE's in each mineral phase or
sample (and analytical accuracy). The Chondrite plots should produce a
smooth plot across the REE series if the sample being examined has not
experienced preferential removal of elements. The Chondrite plots for the
six Castillo composites are shown in Figure B2.
The plots show a smooth transition in normalised concentration from element to
element which provides confidence in the analytical accuracy. The Eu anomaly
is normal and is indicative of weathering through the geological history of
the deposit (and is seen in clays, monazite, xenotime, or bastnasite
deposits). The slight variation in Ce is common and may be an indication of
dominant Ce mineralogy in certain samples. The slopes of the plots indicate
that the distributions of REEs are similar in all the composites except for RT
001RC A (fresh Pegmatite). The slope of RT-001RC A indicates a significantly
lower HRE/LRE ratio than the other five samples.
FIGURE B2: CHONDRITE PLOT OF HEAD SAMPLES
Source: ANSTO 2023
FIGURE B3: RARE EARTH ELEMENT COMPOSITION OF HEAD SAMPLES (PPM)
Elements TT-002RC TT-005DD FG-003RC FG-004RC RT-001RC RT-001RC A
La 199 283 335 215 47 206
Ce 450 423 488 411 90 410
Pr 49 75 62 47 10 47
Nd 203 316 220 174 37 174
Sm 43 67 36 32 7 29
Eu 10 16 6 5 1 2
Gd 44 66 28 21 5 18
Tb 7 10 4 3 1 1
Dy 37 53 20 17 4 3
Ho 7 9 3 3 1 0
Er 18 26 10 8 2 0
Tm 2 3 1 1 0 0
Yb 14 21 8 7 2 0
Lu 2 3 1 1 0 0
Y 169 261 88 71 20 7
LREE 901 1097 1105 847 184 837
HREE 185 274 117 96 23 53
Magnets 296 454 305 241 52 226
TRE+Y 1254 1632 1309 1014 227 897
MREO 347 532 358 282 61 265
TREYO 1509 1958 1570 1218 273 1076
MREO/TREO (%) 23.0 27.1 22.8 23.2 22.7 24.7
Notes:
1. LREE = La, Ce, Pr, Nd; HREE = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,
Yb, Lu.
2. Magnets = Pr, Nd, Tb, Dy; MREO = magnet oxides.
3. TREO = Total oxides.
Source: ANSTO
FIGURE B4: GANGUE COMPOSITION OF HEAD SAMPLES
Elements Unit TT-002RC TT-005DD FG-003RC FG-004RC RT-001RC RT-001RC A
Al wt% 8.65 8.50 8.68 10.3 9.14 11.1
Ca wt% 0.93 0.29 0.50 0.45 0.66 3.03
Cu wt% 1.15 0.106 0.009 0.002 0.002 0.006
Fe wt% 10.1 13.2 3.44 1.26 2.46 6.87
K wt% 0.70 0.94 1.08 0.90 1.53 3.48
Mg wt% 0.95 1.14 1.13 1.13 0.95 2.39
Mn wt% 0.47 0.25 0.02 0.005 0.009 0.07
Na wt% 1.55 0.85 4.23 6.34 4.18 2.59
P wt% 0.05 0.07 0.04 0.11 0.05 0.05
Sc ppm 57 48 24 29 15 10
Si wt% 25.1 24.2 30.3 29.5 30.6 22.9
Th ppm 2 4 17 21 18 102
U ppm 8 14 19 10 3 8
TREE+Y ppm 1254 1632 1309 1014 227 897
Source: Indratti (2023)
APPENDIX C: JORC CODE, 2012 EDITION TABLE 1 - ANSTO METALLURGICAL TESTING
Section 1: Sampling Techniques and Data
Criteria JORC Code explanation Commentary
Sampling techniques Nature and quality of sampling (e.g., cut channels, random chips, or specific The samples described in Table B1 were derived from the EL 8434 October 2022
specialised industry standard measurement tools appropriate to the minerals drilling program, as follows:
under investigation, such as down hole gamma sondes, or handheld XRF
instruments, etc.). These examples should not be taken as limiting the broad Diamond Drilling (DDH)
meaning of sampling.
Diamond drilling of HQ diameter (TT_005DD) was completed to 137.7m r in the
Include reference to measures taken to ensure sample representivity and the completed program and was located 5m away from a RC hole already drilled (TT_
appropriate calibration of any measurement tools or systems used. 003RC).
Aspects of the determination of mineralisation that are Material to the Public Reverse Circulation ('RC') Drilling
Report.
RC drilling at Fence Gossan with samples submitted for analysis using the
In cases where 'industry standard' work has been done this would be relatively above-mentioned methodologies was used to obtain a representative sample by
simple (e.g., 'reverse circulation drilling was used to obtain 1 m samples means of riffle splitting.
from which 3 kg was pulverised to produce a 30g charge for fire assay'). In
other cases, more explanation may be required, such as where there is coarse Four (4) reverse circulation (RC) holes for a total of 516m have been
gold that has inherent sampling problems. Unusual commodities or completed at the Fence Gossan Prospect.
mineralisation types (eg submarine nodules) may warrant disclosure of detailed
information. Four (4) RC holes were completed at Reefs Tank for a total of 564m.
At Tors Tank, four (4) RC holes for a total of 625.7m (including the cored
hole) were completed.
The RC drilling technique was used to obtain a representative sample by means
of a cone or riffle splitter with samples submitted for assay by mixed acid
digestion and analysis via ICP-MS + ICP-AES with anticipated reporting a suite
of 48 elements (sulphur >10% by LECO)
Drilling techniques Drill type (e.g., core, reverse circulation, open-hole hammer, rotary air Drilling consisted of reverse circulation, and HQ diamond coring. One cored
blast, auger, Bangka, sonic, etc.) and details (e.g., core diameter, triple or hole of HQ (61mm) diameter was completed at Tors Tank (TT005DD) after all the
standard tube, depth of diamond tails, face-sampling bit or other type, RC holes had been completed.
whether core is oriented and if so, by what method, etc.).
Diamond drilling will be completed with standard diameter, conventional HQ and
NQ with historical holes typically utilizing RC and percussion pre-collars to
an average 30 metres (see Drillhole Information for further details).
Drill sample recovery Method of recording and assessing core and chip sample recoveries and results Reverse Circulation ('RC') Drilling - Reverse circulation sample recoveries
assessed. were visually estimated during drilling programs. Where the estimated sample
recovery was below 100% this was recorded in field logs by means of
Measures taken to maximise sample recovery and ensure representative nature of qualitative observation.
the samples.
Reverse circulation drilling employed sufficient air (using a compressor and
Whether a relationship exists between sample recovery and grade and whether booster) to maximise sample recovery.
sample bias may have occurred due to preferential loss/gain of fine/coarse
material. Historical cored drillholes by North Broken Hill, CRA , and Pasminco were well
documented and generally have >90% core recovery.
No relationship between sample recovery and grade has been observed.
Logging Whether core and chip samples have been geologically and geotechnically logged The drilling that did occur was completed to modern-day standards. In this
to a level of detail to support appropriate Mineral Resource estimation, program at all three areas holes were completed to varying depths ranging from
mining studies and metallurgical studies. 100-220m.
Whether logging is qualitative or quantitative in nature. Core (or costean, No downhole geophysical logging took place; however, measurements of magnetic
channel, etc) photography. susceptibility were taken at the same 1m intervals as the PXRF readings were
taken.
The total length and percentage of the relevant intersections logged.
Sub-sampling techniques and sample preparation If core, whether cut or sawn and whether quarter, half or all core taken. Core samples will be hand-split or sawn with re-logging of available
historical core indicating a 70:30 (retained: assayed) split was typical. The
If non-core, whether riffled, tube sampled, rotary split, etc and whether variation of sample ratios noted are considered consistent with the
sampled wet or dry. sub-sampling technique (hand-splitting).
For all sample types, the nature, quality, and appropriateness of the sample No second half samples were submitted for analysis, but duplicates have been
preparation technique. taken at a frequency of 1:20 in samples collected.
Quality control procedures adopted for all sub-sampling stages to maximise It is considered water planned to be used for core cutting is unprocessed and
representivity of samples. unlikely to have introduced sample contamination.
Measures taken to ensure that the sampling is representative of the in-situ Procedures relating to the definition of the line of cutting or splitting are
material collected, including for instance results for field not available. It is expected that 'standard industry practice' for the
duplicate/second-half sampling. period was applied to maximize sample representivity.
Whether sample sizes are appropriate to the grain size of the material being Quarter core will be submitted to ALS for chemical analysis using industry
sampled. standard sample preparation and analytical techniques.
The sample interval details and grades quoted for cored intervals described in
various maps in the main section are given in previous ASX releases (Castillo
Copper 2022a, b, c, 2023a).
Quality of assay data and laboratory tests The nature, quality and appropriateness of the assaying and laboratory The following rare earth elements were analysed using ME-MS61R Sample
procedures used and whether the technique is considered partial or total. Decomposition is by HF-HNO(3)-HClO(4) acid digestion, HCl leach (GEO-4A01).
The Analytical Method for Silver is shown below:
For geophysical tools, spectrometers, handheld XRF instruments, etc, the
Element Symbol Units Lower Limit Upper Limit
parameters used in determining the analysis including instrument make and Silver Ag ppm 0.01 100
model, reading times, calibrations factors applied and their derivation, etc.
Inductively Coupled Plasma - Atomic Emission Spectroscopy (ICP - AES)
Nature of quality control procedures adopted (eg standards, blanks, Inductively Coupled Plasma - Mass Spectrometry (ICP-MS)
duplicates, external laboratory checks) and whether acceptable levels of
accuracy (i.e. lack of bias) and precision have been established. Aprepared sample (0.25 g) is digested with perchloric, nitric, hydrofluoric,
and hydrochloric acids. The residue is topped up with dilute hydrochloric acid
and analysed by inductively coupled plasma atomic emission spectrometry.
Following this analysis, the results are reviewed for high concentrations of
bismuth, mercury, molybdenum, silver, and tungsten and diluted accordingly.
Samples meeting this criterion are then analysed by inductively coupled
plasma-mass spectrometry. Results are corrected for spectral interelement
interferences.
Four acid digestions can dissolve most minerals: however, although the term
"near total" is used, depending on the sample matrix, not all elements are
quantitatively extracted.
Results for the additional rare earth elements will represent the acid
leachable portion of the rare earth elements and as such, cannot be used, for
instance to do a chondrite plot.
Geochemical Procedure
Element geochemical procedure reporting units and limits are listed below:
Element Symbol Units Lower Limit Upper Limit
Aluminum Al % 0.01 50
Arsenic As ppm 0.2 10 000
Barium Ba ppm 10 10 000
Beryllium Be ppm 0.05 1 000
Bismuth Bi ppm 0.01 10 000
Calcium Ca % 0.01 50
Cadmium Cd ppm 0.02 1 000
Cerium Ce ppm 0.01 500
Cobalt Co ppm 0.1 10 000
Chromium Cr ppm 1 10 000
Cesium Cs ppm 0.05 500
Copper Cu ppm 0.2 10 000
Iron Fe % 0.01 50
Gallium Ga ppm 0.05 10 000
Germanium Ge ppm 0.05 500
Hafnium Hf ppm 0.1 500
Indium In ppm 0.005 500
Potassium K % 0.01 10
Lanthanum La ppm 0.5 10 000
Lithium Li ppm 0.2 10 000
Magnesium Mg % 0.01 50
Molybdenum Mo ppm 0.05 10 000
Sodium Na % 0.01 10
Niobium Nb ppm 0.1 500
Nickel Ni ppm 0.2 10 000
Phosphorous P ppm 10 10 000
Lead Pb ppm 0.5 10 000
Rubidium Rb ppm 0.1 10 000
Rhenium Re ppm 0.002 50
Sulphur S % 0.01 10
Antimony Sb ppm 0.05 10 000
Scandium Sc ppm 0.1 10 000
Selenium Se ppm 1 1 000
Tin Sn ppm 0.2 500
Strontium Sr ppm 0.2 10 000
Tantalum Ta ppm 0.05 100
Tellurium Te ppm 0.05 500
Thorium Th ppm 0.2 10 000
Titanium Ti % 0.005 10
Thallium Tl ppm 0.02 10 000
Uranium U ppm 0.1 10 000
Vanadium V ppm 1 10 000
Tungsten W ppm 0.1 10 000
Method ME-MS81
This method involves a lithium borate fusion prior to acid dissolution and
ICP- MS analysis provides the most quantitative analytical approach for a
broad suite of trace elements. Options for adding the whole rock elements
from an |CP - AES analysis on the same fusion, or base metals from a separate
four acid digestion, are available.
Lower and upper detection limits are given below:
Element Symbol Units Lower Limit Upper Limit
Yttrium Y ppm 0.1 500
Zinc Zn ppm 2 10 000
Zirconium Zr ppm 0.5 500
Dysprosium Dy ppm 0.05 1 000
Erbium Er ppm 0.03 1 000
Europium Eu ppm 0.03 1 000
Gadolinium Gd ppm 0.05 1 000
Holmium Ho ppm 0.01 1 000
Lutetium Lu ppm 0.01 1 000
Neodymium Nd ppm 0.1 1 000
Praseodymium Pr ppm 0.03 1 000
Samarium Sm ppm 0.03 1 000
Terbium Tb ppm 0.01 1 000
Thulium Tm ppm 0.01 1 000
Ytterbium Yb ppm 0.03 1 000
Inductively Coupled Plasma - Atomic Emission Spectroscopy (ICP - AES)
Inductively Coupled Plasma - Mass Spectrometry (ICP-MS)
A prepared sample (0.25 g) is digested with perchloric, nitric, hydrofluoric,
and hydrochloric acids. The residue is topped up with dilute hydrochloric acid
and analysed by inductively coupled plasma atomic emission spectrometry.
Following this analysis, the results are reviewed for high concentrations of
bismuth, mercury, molybdenum, silver, and tungsten and diluted accordingly.
Samples meeting this criterion are then analysed by inductively coupled
plasma-mass spectrometry. Results are corrected for spectral interelement
interferences.
Four acid digestions can dissolve most minerals: however, although the term
"near total" is used, depending on the sample matrix, not all elements are
quantitatively extracted.
Results for the additional rare earth elements will represent the acid
leachable portion of the rare earth elements and as such, cannot be used, for
instance to do a chondrite plot.
Geochemical Procedure
Element geochemical procedure reporting units and limits are listed below:
Element Symbol Units Lower Limit Upper Limit
Aluminum Al % 0.01 50
Arsenic As ppm 0.2 10 000
Barium Ba ppm 10 10 000
Beryllium Be ppm 0.05 1 000
Bismuth Bi ppm 0.01 10 000
Calcium Ca % 0.01 50
Cadmium Cd ppm 0.02 1 000
Cerium Ce ppm 0.01 500
Cobalt Co ppm 0.1 10 000
Chromium Cr ppm 1 10 000
Cesium Cs ppm 0.05 500
Copper Cu ppm 0.2 10 000
Iron Fe % 0.01 50
Gallium Ga ppm 0.05 10 000
Germanium Ge ppm 0.05 500
Hafnium Hf ppm 0.1 500
Indium In ppm 0.005 500
Potassium K % 0.01 10
Lanthanum La ppm 0.5 10 000
Lithium Li ppm 0.2 10 000
Magnesium Mg % 0.01 50
Molybdenum Mo ppm 0.05 10 000
Sodium Na % 0.01 10
Niobium Nb ppm 0.1 500
Nickel Ni ppm 0.2 10 000
Phosphorous P ppm 10 10 000
Lead Pb ppm 0.5 10 000
Rubidium Rb ppm 0.1 10 000
Rhenium Re ppm 0.002 50
Sulphur S % 0.01 10
Antimony Sb ppm 0.05 10 000
Scandium Sc ppm 0.1 10 000
Selenium Se ppm 1 1 000
Tin Sn ppm 0.2 500
Strontium Sr ppm 0.2 10 000
Tantalum Ta ppm 0.05 100
Tellurium Te ppm 0.05 500
Thorium Th ppm 0.2 10 000
Titanium Ti % 0.005 10
Thallium Tl ppm 0.02 10 000
Uranium U ppm 0.1 10 000
Vanadium V ppm 1 10 000
Tungsten W ppm 0.1 10 000
Method ME-MS81
This method involves a lithium borate fusion prior to acid dissolution and
ICP- MS analysis provides the most quantitative analytical approach for a
broad suite of trace elements. Options for adding the whole rock elements
from an |CP - AES analysis on the same fusion, or base metals from a separate
four acid digestion, are available.
Lower and upper detection limits are given below:
Element Symbol Units Lower Limit Upper Limit
Yttrium Y ppm 0.1 500
Zinc Zn ppm 2 10 000
Zirconium Zr ppm 0.5 500
Dysprosium Dy ppm 0.05 1 000
Erbium Er ppm 0.03 1 000
Europium Eu ppm 0.03 1 000
Gadolinium Gd ppm 0.05 1 000
Holmium Ho ppm 0.01 1 000
Lutetium Lu ppm 0.01 1 000
Neodymium Nd ppm 0.1 1 000
Praseodymium Pr ppm 0.03 1 000
Samarium Sm ppm 0.03 1 000
Terbium Tb ppm 0.01 1 000
Thulium Tm ppm 0.01 1 000
Ytterbium Yb ppm 0.03 1 000
· Laboratory inserted standards, blanks and duplicates were
analysed per industry standard practice. There was no evidence of bias from
these results.
Verification of sampling and assaying The verification of significant intersections by either independent or · Two of the drillholes have been twinned, at Tors Tank where
alternative company personnel. TT_005DD was drilled next to TT_003RC.
The use of twinned holes. · Conversion of elemental analysis (REE parts per million) to
stoichiometric oxide (REO parts per million) was undertaken by ROM geological
Documentation of primary data, data entry procedures, data verification, data staff using the below element to stoichiometric oxide conversion factors
storage (physical and electronic) protocols. (https://www.jcu.edu.au/news/releases/2020/march/rare-earth-metals-an-untapped-resource)
Discuss any adjustment to assay data.
Table C1-1: Element -Conversion Factor -Oxide Form
Ce 1.2284 CeO(2)
Dy 1.1477 Dy(2)O(3)
Er 1.1435 Er(2)O(3)
Eu 1.1579 Eu(2)O(3)
Gd 1.1526 Gd(2)O(3)
Ho 1.1455 Ho(2)O(3)
La 1.1728 La(2)O(3)
Lu 1.1371 Lu(2)O(3)
Nd 1.1664 Nd(2)O(3)
Pr 1.2083 Pr(6)O(11)
Sm 1.1596 Sm(2)O(3)
Tb 1.1762 Tb(4)O(7)
Tm 1.1421 Tm(2)O(3)
Y 1.2699 Y(2)O(3)
Yb 1.1387 Yb(2)O(3)
Rare earth oxide is the industry accepted form for reporting rare earths. The
following calculations are used for compiling REO into their reporting and
evaluation groups:
TREO (Total Rare Earth Oxide) = La(2)O(3) + CeO(2) + Pr(6)O(11) + Nd(2)O(3) +
Sm(2)O(3) + Eu(2)O(3) + Gd(2)O(3) + Tb(4)O(7) + Dy(2)O(3) + Ho(2)O(3) +
Er(2)O(3) + Tm(2)O(3) + Yb(2)O(3) + Y(2)O(3) + Lu(2)O(3).
TREO-Ce = TREO - CeO(2)
LREO (Light Rare Earth Oxide) = La(2)O(3) + CeO(2) + Pr(6)O(11) + Nd(2)O(3) +
Sm(2)O(3)
HREO (Heavy Rare Earth Oxide) = Eu(2)O(3) + Gd(2)O(3) + Tb(4)O(7) + Dy(2)O(3)
+ Ho(2)O(3) + Er(2)O(3) + Tm2O3 + Yb2O3 + Y2O3 + Lu2O3
CREO (Critical Rare Earth Oxide) = Nd(2)O(3) + Eu(2)O(3) + Tb(4)O(7) +
Dy(2)O(3) + Y(2)O(3)
MREO (Magnetic Rare Earth Oxide) = Pr(6)O(11) + Nd(2)O(3) + Tb(4)O(7) +
Dy(2)O(3). (as advised by ANSTO)
Previously, Castillo Copper had reported MREO (Magnetic Rare Earth Oxide) as =
Pr(6)O(11) + Nd(2)O(3) + Sm(2)O(3) + Gd(2)O(3) + Tb(4)O(7) + Dy(2)O(3).
Total Rare Earth Oxides (TREO) Example Calculation:
To calculate TREO an oxide conversion "factor" is applied to each rare-earth
element assay. The "factor" equates an elemental assay to an oxide
concentration for each element. Below is an example of the factor calculation
for Lanthanum (La):
o Relative Atomic Mass (La) = 138.9055
o Relative Atomic Mass (O) = 15.9994
o Oxide Formula = La(2)O(3)
o Oxide Conversion Factor = 1/ ((2x 138.9055)/(2x 138.9055 + 3x 15.9994))
Oxide Conversion Factor = 1.173 (3dp)
None of the historical data has been adjusted.
Location of data points Accuracy and quality of surveys used to locate drill holes (collar and All drillholes and samples have been converted to MGA94 (Zone 54). The holes
down-hole surveys), trenches, mine workings and other locations used in were originally surveyed with handheld GPS, and were subsequently resurveyed
Mineral Resource estimation. by a more accurate DGPS survey from GMC Surveying. It is thus estimated that
locational accuracy therefore varies between 0.1-0.2m
Specification of the grid system used.
The quality of topographic control (a combination of drone survey over the
Quality and adequacy of topographic control. Fence Gossan area and GSNSW 1 sec DEM for the remainder) is deemed adequate
for the purposes of the exploration drilling program.
Data spacing and distribution Data spacing for reporting of Exploration Results. The average sample spacing from the current drilling program across the tenure
varies per prospect, and sample type, as listed in Table C1-2, below:
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.
Whether sample compositing has been applied.
Table C1-2: EL 8434 Drillhole Spacing
Prospect Drillholes Completed RMS Drillhole Spacing (m)
The Sisters Not yet
Iron Blow Not Yet
Tors Tank 4 127
Fence Gossan 4 208
Ziggy's Hill n/a n/a
Reefs Tank 1 n/a
The Datamine software allows creation of fixed length samples from the
original database given a set of stringent rules.
Sample locations were previously shown by plans in Castillo Copper (2023a).
Orientation of data in relation to geological structure Whether the orientation of sampling achieves unbiased sampling of possible Historical drill holes at the BHAE are typically drilled vertically for auger
structures and the extent to which this is known, considering the deposit and RAB types (drilled along section lines) and angled at -55˚ or -60˚ to
type. the horizontal and drilled perpendicular to the mineralised trend for RC and
DDH.
If the relationship between the drilling orientation and the orientation of
key mineralised structures is considered to have introduced a sampling bias, Drilling orientations are adjusted along strike to accommodate folded
this should be assessed and reported if material. geological sequences. All Fence Gossan holes were designed to drill toward
grid south at an inclination of 60 degrees from horizontal.
The drilling orientation is not considered to have introduced a sampling bias
on assessment of the current geological interpretation.
Geological mapping by various companies has reinforced that the strata dips
variously between 5 and 65 degrees.
Sample security The measures taken to ensure sample security. Sample security procedures are considered 'industry standard' for the current
period.
Samples obtained during drilling completed between 4/10/22 to the 10/10/22
were transported by exploration employees or an independent courier directly
from Broken Hill to ALS Laboratory, Adelaide. Samples selected for
metallurgical testing were then shipped to ANSTO in Sydney NSW.
The Company considers that risks associated with sample security are limited
given the nature of the targeted mineralisation.
Audits or reviews The results of any audits or reviews of sampling techniques and data. No external audits or reviews have yet been undertaken. The reporting of head
grades by ANSTO internal laboratory work matches that previously reported by
ALS work conducted on behalf of Castillo Copper (Biggs 2023; Castillo Copper
2023a).
Inductively Coupled Plasma - Atomic Emission Spectroscopy (ICP - AES)
Inductively Coupled Plasma - Mass Spectrometry (ICP-MS)
A prepared sample (0.25 g) is digested with perchloric, nitric, hydrofluoric,
and hydrochloric acids. The residue is topped up with dilute hydrochloric acid
and analysed by inductively coupled plasma atomic emission spectrometry.
Following this analysis, the results are reviewed for high concentrations of
bismuth, mercury, molybdenum, silver, and tungsten and diluted accordingly.
Samples meeting this criterion are then analysed by inductively coupled
plasma-mass spectrometry. Results are corrected for spectral interelement
interferences.
Four acid digestions can dissolve most minerals: however, although the term
"near total" is used, depending on the sample matrix, not all elements are
quantitatively extracted.
Results for the additional rare earth elements will represent the acid
leachable portion of the rare earth elements and as such, cannot be used, for
instance to do a chondrite plot.
Geochemical Procedure
Element geochemical procedure reporting units and limits are listed below:
Element Symbol Units Lower Limit Upper Limit
Aluminum Al % 0.01 50
Arsenic As ppm 0.2 10 000
Barium Ba ppm 10 10 000
Beryllium Be ppm 0.05 1 000
Bismuth Bi ppm 0.01 10 000
Calcium Ca % 0.01 50
Cadmium Cd ppm 0.02 1 000
Cerium Ce ppm 0.01 500
Cobalt Co ppm 0.1 10 000
Chromium Cr ppm 1 10 000
Cesium Cs ppm 0.05 500
Copper Cu ppm 0.2 10 000
Iron Fe % 0.01 50
Gallium Ga ppm 0.05 10 000
Germanium Ge ppm 0.05 500
Hafnium Hf ppm 0.1 500
Indium In ppm 0.005 500
Potassium K % 0.01 10
Lanthanum La ppm 0.5 10 000
Lithium Li ppm 0.2 10 000
Magnesium Mg % 0.01 50
Molybdenum Mo ppm 0.05 10 000
Sodium Na % 0.01 10
Niobium Nb ppm 0.1 500
Nickel Ni ppm 0.2 10 000
Phosphorous P ppm 10 10 000
Lead Pb ppm 0.5 10 000
Rubidium Rb ppm 0.1 10 000
Rhenium Re ppm 0.002 50
Sulphur S % 0.01 10
Antimony Sb ppm 0.05 10 000
Scandium Sc ppm 0.1 10 000
Selenium Se ppm 1 1 000
Tin Sn ppm 0.2 500
Strontium Sr ppm 0.2 10 000
Tantalum Ta ppm 0.05 100
Tellurium Te ppm 0.05 500
Thorium Th ppm 0.2 10 000
Titanium Ti % 0.005 10
Thallium Tl ppm 0.02 10 000
Uranium U ppm 0.1 10 000
Vanadium V ppm 1 10 000
Tungsten W ppm 0.1 10 000
Method ME-MS81
This method involves a lithium borate fusion prior to acid dissolution and
ICP- MS analysis provides the most quantitative analytical approach for a
broad suite of trace elements. Options for adding the whole rock elements
from an |CP - AES analysis on the same fusion, or base metals from a separate
four acid digestion, are available.
Lower and upper detection limits are given below:
Element Symbol Units Lower Limit Upper Limit
Yttrium Y ppm 0.1 500
Zinc Zn ppm 2 10 000
Zirconium Zr ppm 0.5 500
Dysprosium Dy ppm 0.05 1 000
Erbium Er ppm 0.03 1 000
Europium Eu ppm 0.03 1 000
Gadolinium Gd ppm 0.05 1 000
Holmium Ho ppm 0.01 1 000
Lutetium Lu ppm 0.01 1 000
Neodymium Nd ppm 0.1 1 000
Praseodymium Pr ppm 0.03 1 000
Samarium Sm ppm 0.03 1 000
Terbium Tb ppm 0.01 1 000
Thulium Tm ppm 0.01 1 000
Ytterbium Yb ppm 0.03 1 000
· Laboratory inserted standards, blanks and duplicates were
analysed per industry standard practice. There was no evidence of bias from
these results.
Verification of sampling and assaying
The verification of significant intersections by either independent or
alternative company personnel.
The use of twinned holes.
Documentation of primary data, data entry procedures, data verification, data
storage (physical and electronic) protocols.
Discuss any adjustment to assay data.
· Two of the drillholes have been twinned, at Tors Tank where
TT_005DD was drilled next to TT_003RC.
· Conversion of elemental analysis (REE parts per million) to
stoichiometric oxide (REO parts per million) was undertaken by ROM geological
staff using the below element to stoichiometric oxide conversion factors
(https://www.jcu.edu.au/news/releases/2020/march/rare-earth-metals-an-untapped-resource)
Table C1-1: Element -Conversion Factor -Oxide Form
Ce 1.2284 CeO(2)
Dy 1.1477 Dy(2)O(3)
Er 1.1435 Er(2)O(3)
Eu 1.1579 Eu(2)O(3)
Gd 1.1526 Gd(2)O(3)
Ho 1.1455 Ho(2)O(3)
La 1.1728 La(2)O(3)
Lu 1.1371 Lu(2)O(3)
Nd 1.1664 Nd(2)O(3)
Pr 1.2083 Pr(6)O(11)
Sm 1.1596 Sm(2)O(3)
Tb 1.1762 Tb(4)O(7)
Tm 1.1421 Tm(2)O(3)
Y 1.2699 Y(2)O(3)
Yb 1.1387 Yb(2)O(3)
Rare earth oxide is the industry accepted form for reporting rare earths. The
following calculations are used for compiling REO into their reporting and
evaluation groups:
TREO (Total Rare Earth Oxide) = La(2)O(3) + CeO(2) + Pr(6)O(11) + Nd(2)O(3) +
Sm(2)O(3) + Eu(2)O(3) + Gd(2)O(3) + Tb(4)O(7) + Dy(2)O(3) + Ho(2)O(3) +
Er(2)O(3) + Tm(2)O(3) + Yb(2)O(3) + Y(2)O(3) + Lu(2)O(3).
TREO-Ce = TREO - CeO(2)
LREO (Light Rare Earth Oxide) = La(2)O(3) + CeO(2) + Pr(6)O(11) + Nd(2)O(3) +
Sm(2)O(3)
HREO (Heavy Rare Earth Oxide) = Eu(2)O(3) + Gd(2)O(3) + Tb(4)O(7) + Dy(2)O(3)
+ Ho(2)O(3) + Er(2)O(3) + Tm2O3 + Yb2O3 + Y2O3 + Lu2O3
CREO (Critical Rare Earth Oxide) = Nd(2)O(3) + Eu(2)O(3) + Tb(4)O(7) +
Dy(2)O(3) + Y(2)O(3)
MREO (Magnetic Rare Earth Oxide) = Pr(6)O(11) + Nd(2)O(3) + Tb(4)O(7) +
Dy(2)O(3). (as advised by ANSTO)
Previously, Castillo Copper had reported MREO (Magnetic Rare Earth Oxide) as =
Pr(6)O(11) + Nd(2)O(3) + Sm(2)O(3) + Gd(2)O(3) + Tb(4)O(7) + Dy(2)O(3).
Total Rare Earth Oxides (TREO) Example Calculation:
To calculate TREO an oxide conversion "factor" is applied to each rare-earth
element assay. The "factor" equates an elemental assay to an oxide
concentration for each element. Below is an example of the factor calculation
for Lanthanum (La):
o Relative Atomic Mass (La) = 138.9055
o Relative Atomic Mass (O) = 15.9994
o Oxide Formula = La(2)O(3)
o Oxide Conversion Factor = 1/ ((2x 138.9055)/(2x 138.9055 + 3x 15.9994))
Oxide Conversion Factor = 1.173 (3dp)
None of the historical data has been adjusted.
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.
Specification of the grid system used.
Quality and adequacy of topographic control.
All drillholes and samples have been converted to MGA94 (Zone 54). The holes
were originally surveyed with handheld GPS, and were subsequently resurveyed
by a more accurate DGPS survey from GMC Surveying. It is thus estimated that
locational accuracy therefore varies between 0.1-0.2m
The quality of topographic control (a combination of drone survey over the
Fence Gossan area and GSNSW 1 sec DEM for the remainder) is deemed adequate
for the purposes of the exploration drilling program.
Data spacing and distribution
Data spacing for reporting of Exploration Results.
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.
Whether sample compositing has been applied.
The average sample spacing from the current drilling program across the tenure
varies per prospect, and sample type, as listed in Table C1-2, below:
Table C1-2: EL 8434 Drillhole Spacing
Prospect Drillholes Completed RMS Drillhole Spacing (m)
The Sisters Not yet
Iron Blow Not Yet
Tors Tank 4 127
Fence Gossan 4 208
Ziggy's Hill n/a n/a
Reefs Tank 1 n/a
The Datamine software allows creation of fixed length samples from the
original database given a set of stringent rules.
Sample locations were previously shown by plans in Castillo Copper (2023a).
Orientation of data in relation to geological structure
Whether the orientation of sampling achieves unbiased sampling of possible
structures and the extent to which this is known, considering the deposit
type.
If the relationship between the drilling orientation and the orientation of
key mineralised structures is considered to have introduced a sampling bias,
this should be assessed and reported if material.
Historical drill holes at the BHAE are typically drilled vertically for auger
and RAB types (drilled along section lines) and angled at -55˚ or -60˚ to
the horizontal and drilled perpendicular to the mineralised trend for RC and
DDH.
Drilling orientations are adjusted along strike to accommodate folded
geological sequences. All Fence Gossan holes were designed to drill toward
grid south at an inclination of 60 degrees from horizontal.
The drilling orientation is not considered to have introduced a sampling bias
on assessment of the current geological interpretation.
Geological mapping by various companies has reinforced that the strata dips
variously between 5 and 65 degrees.
Sample security
The measures taken to ensure sample security.
Sample security procedures are considered 'industry standard' for the current
period.
Samples obtained during drilling completed between 4/10/22 to the 10/10/22
were transported by exploration employees or an independent courier directly
from Broken Hill to ALS Laboratory, Adelaide. Samples selected for
metallurgical testing were then shipped to ANSTO in Sydney NSW.
The Company considers that risks associated with sample security are limited
given the nature of the targeted mineralisation.
Audits or reviews
The results of any audits or reviews of sampling techniques and data.
No external audits or reviews have yet been undertaken. The reporting of head
grades by ANSTO internal laboratory work matches that previously reported by
ALS work conducted on behalf of Castillo Copper (Biggs 2023; Castillo Copper
2023a).
SECTION 2: REPORTING OF EXPLORATION RESULTS
Criteria JORC Code explanation Commentary
Mineral tenement and land tenure status Type, reference name/number, location and ownership including agreements or EL 8434 is located about 28km east of Broken Hill whilst EL 8435 is 16km east
material issues with third parties such as joint ventures, partnerships, of Broken Hill. Both tenures are approximately 900km northwest of Sydney in
overriding royalties, native title interests, historical sites, wilderness or far western New South Wales (Figures C2-1 and C2-2 in Appendix A, above).
national park and environmental settings.
EL 8434 and EL 8435 were both granted on the 2(nd of) June 2016 to Squadron
The security of the tenure held at the time of reporting along with any known Resources for a term of five (5) years for Group One Minerals. On the 25(th
impediments to obtaining a licence to operate in the area. of) May 2020, Squadron Resources changed its name to Wyloo Metals Pty Ltd
(Wyloo). In December 2020 the tenure was transferred from Wyloo Metals to
Broken Hill Alliance Pty Ltd a 100% subsidiary company of Castillo Copper
Limited. Both tenures were renewed on the 12(th of) August 2021 for a
further six (6) years and are due to expire on the 2(nd of) June 2027.
EL 8434 lies across two (2) 1:100,000 geology map sheets Redan 7233 and
Taltingan 7234, and two (2) 1:250,000 geology map sheets, SI54-3 Menindee, and
SH54-15 Broken Hill in the county of Yancowinna. EL 8434 consists of one
hundred and eighty-six (186) units) in the Adelaide and Broken Hill
1:1,000,000 Blocks covering an area of approximately 580km(2).
EL 8435 is located on the 1:100,000 geology map sheet Taltingan 7234, and the
1:250,000 geology map sheet SH/54-15 Broken Hill in the county of
Yancowinna. EL 8435 consists of twenty-two (22) units (Table 1) in the
Broken Hill 1:1,000,000 Blocks covering an area of approximately 68km(2).
Access to the tenures from Broken Hill is via the sealed Barrier Highway.
This road runs north-east to south-west through the northern portion of EL
8434, passes the southern tip of EL 8435 eastern section and through the
middle of the western section of EL 8435. Access is also available via the
Menindee Road which runs north-west to south-east through the southern section
of the EL 8434. The Orange to Broken Hill Rail line also dissects EL 8435
western section the middle and then travels north-west to south-east slicing
through the eastern arm of EL 8434 (Figure C2-1).
Figure C2-1: EL 8434 and EL 8435 General Location Map
Exploration done by other parties Acknowledgment and appraisal of exploration by other parties. Explorers who were actively involved over longer historical periods in various
parts of EL8434 were: - North Broken Hill Ltd, CRAE Exploration, Major Mining
Ltd and Broken Hill Metals NL, Pasminco Exploration Ltd, Normandy Exploration
Ltd, PlatSearch NL/Inco Ltd/ EGC Pty Ltd JV and the Western Plains Gold
Ltd/PlatSearch/EGC Pty Ltd JV.
A comprehensive summary of work by previous explorers was presented in Leyh
(2009). However, more recently, follow-up field reconnaissance of areas of
geological interest, including most of the prospective zones, was carried out
by EGC Pty Ltd over the various licenses. This work, in conjunction with a
detailed interpretation of aeromagnetic, gravity plus RAB / RC drill hole
logging originally led to the identification of at least sixteen higher
priority prospect areas. All these prospects were summarized in considerable
detail in Leyh (2008). Future work programs were then also proposed for each
area. Since then, further compilation work plus detailed geological
reconnaissance mapping and sampling of gossans and lode rocks has been carried
out.
A total of 22 prospects were then recognised on the exploration licence with
at least 12 occurring in and around the tenure.
With less than 45% outcropping Proterozoic terrain within the licence, this
makes it very difficult to explore and is in the main very effectively
screened from the easy application of more conventional exploration
methodologies due to a predominance of extensive Cainozoic cover sequences.
These include recent to young Quaternary soils, sands, clays and older more
resistant, only partially dissected, Tertiary duricrust regolith covered
areas. The depth of the cover ranges from a few metres in the north to over
60 metres in some areas on the southern and central license.
Exploration by EGC Pty Ltd carried out in the field in the first instance has
therefore been heavily reliant upon time consuming systematic geological
reconnaissance mapping and relatable geochemical sampling. These involve a
slow systematic search over low outcropping areas, poorly exposed subcrop and
float areas as well as the progressive development of effective regolith
mapping and sampling tools. This work has been combined with a vast amount
of intermittently acquired past exploration data. The recent data
compilation includes an insufficiently detailed NSWGS regional mapping scale
given the problems involved, plus some regionally extensive, highly variable,
low-level stream and soil BLEG geochemical data sets over much of the area.
There are also a few useful local detailed mapping grids at the higher
priority prospects, and many more numerous widespread regional augers, RAB,
and percussion grid drilling data sets. Geophysical data sets including ground
magnetics, IP and EM over some prospect areas have also been integrated into
the exploration models. These are located mainly in former areas of moderate
interest and most of the electrical survey methods to date in this type of
terrain continue to be of limited application due to the high degree of
weathering and the often prevailing and complex regolith cover constraints.
Between 2007 and 2014 Eaglehawk Geological Consulting has carried out detailed
research, plus compilation and interpretation of a very large volume of
historic exploration data sourced from numerous previous explorers and dating
back to the early 1970's. Most of this data is in non-digital scanned form.
Many hard copy exploration reports (see references) plus several hundred plans
have been acquired from various sources, hard copy printed as well as
downloaded as scans from the Geological Survey of NSW DIGS system. They also
conducted field mapping, costean mapping and sampling, and rock chip sampling
and analysis.
Work Carried out by Squadron Resources and Whyloo Metals 2016-2020
Research during Year 1 by Squadron Resources revealed that the PGE-rich,
sulphide-bearing ultramafic rocks in the Broken Hill region have a
demonstrably alkaline affinity. This indicates a poor prospectivity for
economic accumulations of sulphide on an empirical basis (e.g., in comparison
to all known economic magmatic nickel sulphide deposits, which have a dominant
tholeiitic affinity). Squadron instead directed efforts toward detecting new
Broken Hill-Type (BHT) deposits that are synchronous with basin formation.
Supporting this modified exploration rationale are the EL's stratigraphic
position, proximity to the Broken Hill line of lode, abundant mapped
alteration (e.g., gahnite and/or garnet bearing exhalative units) and known
occurrences such as the "Sisters" and "Iron Blow" prospects.
The area overlies a potential magmatic Ni-Cu-PGE source region of
metasomatised sub-continental lithospheric mantle (SCLM) identified from a
regional targeting geophysical database. The exploration model at the time
proposed involved remobilization of Ni-Cu-PGE in SCLM and incorporation into
low degree mafic-ultramafic partial melts during a post-Paleoproterozoic plume
event and emplacement higher in the crust as chonoliths/small intrusives -
Voisey's Bay type model. Programs were devised to use geophysics and
geological mapping to locate secondary structures likely to control and
localise emplacement of Ni-Cu-PGE bearing chonoliths. Since EL8434 was
granted, the following has been completed:
• Airborne EM survey.
• Soil and chip sampling.
• Data compilation.
• Geological and logistical reconnaissance.
• Community consultations; and
• Execution of land access agreements
.
Airborne EM Survey
Geotech Airborne Limited was engaged to conduct an airborne EM survey using
their proprietary VTEM system in 2017. A total of 648.92-line kilometres
were flown on a nominal 200m line spacing over a portion of the project area.
Several areas were infilled to 100m line spacing.
The VTEM data was interpreted by Southern Geoscience Consultants Pty Ltd, who
identified a series of anomalies, which were classified as high or low
priority based on anomaly strength (i.e., does the anomaly persist into the
latest channels). Additionally, a cluster of VTEM anomalies at the "Sisters"
prospect have been classified separate due to strong IP effects observed in
the data. Geotech Airborne have provided an IP corrected data and
interpretation of the data has since been undertaken.
Soil and Chip sampling
The VTEM anomalies were followed up by a reconnaissance soil sampling
programme. Spatially clustered VTEM anomalies were grouped, and follow-up soil
lines were designed. Two (2) VTEM anomalies were found to be related to
culture and consequently no soils were collected. Two (2) other anomalies
were sampled which were located above thick alluvium of Stephens Creek and
were therefore not sampled. A line of soil samples was collected over a
relatively undisturbed section at Iron Blow workings and the Sisters Prospect.
One hundred and sixty-six (166) soil samples were collected at a nominal 20cm
depth using a 2mm aluminum sieve. Two (2) rock chips were also collected
during this program. The samples were collected at either 20m or 40m spacing
over selected VTEM anomalies. The samples were pulverised and analysed by
portal XRF at ALS laboratories in Perth.
Each site was annotated with a "Regolith Regime" such that samples from a
depositional environment could be distinguished from those on exposed
Proterozoic bedrock, which were classified as an erosional environment. The
Regolith Regime groups were used for statistical analysis and levelling of the
results. The levelled data reveals strong relative anomalies in zinc at VTEM
anomaly clusters 10, 12 and 14 plus strong anomalous copper at VTEM 17.
Geology Deposit type, geological setting, and style of mineralisation. As the strata is tightly folded, the intersected cobalt-rich layers are
overstated in terms of apparent thickness, however the modelling software
calculates a true, vertical thickness. Cobalt mineralisation is commonly
associated with shears, faults, amphibolites, and a quartz-magnetite rock
within the shears, or on or adjacent to the boundaries of the Himalaya
Formation. In general, most of the cobalt and rare earth element - rich layers
have a north-northwest to north strike.
REE enrichment generally occurs as a 5 to 10-metre-thick zone between the
completely weathered layer and strongly weathered layer and it is targeted for
commercial mining (Figure D2-2). Compared to other REE deposits,
regolith-hosted rare earth element deposits are substantially low-moderate
grade (containing 0.05-0.3 wt.% extractable REEs). Nevertheless, due to its
easy extraction method, low processing costs and large abundance, the
orebodies are generally economic to be extracted (Duuring, (2020); Kanazawa
and Kamitani (2006); and Murakami, H.; Ishihara (2008)).
Figure C2-2: Weathering Profile over REE - Rich Granite
https://en.wikipedia.org/wiki/Regolith-hosted_rare_earth_element_deposits
(https://en.wikipedia.org/wiki/Regolith-hosted_rare_earth_element_deposits)
Weathering profile of regolith hosted REE deposits shown above, the legend is:
(A) Humic layer. (B) Completely weathered layer. (C) Strongly weathered layer.
(D) Weathering front. (E) Unweathered rock.
Most of the REE found in cerium monazite (Ce (PO(4))) which always contains
major to minor amounts of other REE (Nd, La, Pr, Sm etc) replacing Ce. Also,
the mineral often contains trace amounts of U and Th (coupled with Ca). This
will be collaborated with XRD and/or SEM analysis.
Drill hole Information A summary of all information material to the understanding of the exploration Header information about all drillholes and surface samples completed at Reefs
results including a tabulation of the following information for all Material Tank, Tors Tank and Fence Gossan have been tabulated in this release in
drill holes: Appendix B.
o easting and northing of the drill hole collar
o elevation or RL (Reduced Level - elevation above sea level in metres) of
the drill hole collar
o dip and azimuth of the hole
o down hole length and interception depth
o hole length.
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.
Data aggregation methods In reporting Exploration Results, weighting averaging techniques, maximum No metal equivalents have been reported. Rare earth element results have
and/or minimum grade truncations (e.g., cutting of high grades) and cut-off been converted to rare earth oxides as per standard industry practice
grades are usually Material and should be stated. (Castillo Copper 2022c, 2023a).
Where aggregate intercepts incorporate short lengths of high-grade results and No compositing of assay results has taken place, but rather menu options
longer lengths of low-grade results, the procedure used for such aggregation within the Datamine GDB module have been used to create fixed length 1m assay
should be stated and some typical examples of such aggregations should be intervals from the original sampling lengths.
shown in detail.
The rules follow very similarly to those used by the Leapfrog Geo software in
The assumptions used for any reporting of metal equivalent values should be creating fixed length samples.
clearly stated.
Relationship between mineralisation widths and intercept lengths These relationships are particularly important in the reporting of Exploration A database of all the historical borehole sampling has been compiled and
Results. validated. It is uncertain if there is a strong relationship between the
surface sample anomalies to any subsurface anomalous intersections due to the
If the geometry of the mineralisation with respect to the drill hole angle is possible masking by variable Quaternary and Tertiary overburden that varies in
known, its nature should be reported. depth from 0-15m. The mineralisation appears to be secondary enrichment in
the regolith clays and extremely weathered material derived from
If it is not known and only the down hole lengths are reported, there should quartzo-feldspathic pegmatites.
be a clear statement to this effect (e.g., 'down hole length, true width not
known').
Diagrams Appropriate maps and sections (with scales) and tabulations of intercepts Current surface anomalies are shown on maps released on the ASX (Castillo
should be included for any significant discovery being reported These should Copper 2022a, 2022b, 2022c and 2023a). All historical surface sampling has
include, but not be limited to a plan view of drill hole collar locations and had their coordinates converted to MGA94, Zone 54.
appropriate sectional views.
Balanced reporting Where comprehensive reporting of all Exploration Results is not practicable, All recent laboratory analytical results have been recently reported (see
representative reporting of both low and high grades and/or widths should be Castillo Copper 2022a, b, c, 2023a) for assay results.
practiced to avoid misleading reporting of Exploration Results.
Regarding the surface and sampling, no results other than duplicates, blanks
or reference standard assays have been omitted.
Other substantive exploration data Other exploration data, if meaningful and material, should be reported Historical explorers have also conducted airborne and ground gravity,
including (but not limited to): geological observations; geophysical survey magnetic, EM, and IP resistivity surveys over parts of the tenure area but
results; geochemical survey results; bulk samples - size and method of this is yet to be fully georeferenced (especially the ground IP surveys).
treatment; metallurgical test results; bulk density, groundwater, geotechnical Squadron Resources conducted an airborne EM survey in 2017 that covers Iron
and rock characteristics; potential deleterious or contaminating substances. Blow and The Sisters, but not the southern cobalt and REE prospect areas.
Further work The nature and scale of planned further work (e.g., tests for lateral It is recommended that:
extensions or depth extensions or large-scale step-out drilling).
· Assess a wider variety of samples to validate the leach results
Diagrams clearly highlighting the areas of possible extensions, including the across the deposit.
main geological interpretations and future drilling areas, provided this
information is not commercially sensitive. · Consider QEMSCAN mineralogy to identify possible REE phases. This
would confirm the reason for low extractions and inform the likelihood of
increased dissolution under more aggressive acid leach conditions. It would
also inform the possibility of upgrading the REE content by beneficiation
(e.g., screening); and
· Consider additional leach tests using hydrochloric acid to assess
whether increased REE dissolution can be achieved using an alternative
lixiviant for an increased leach duration time but noting that a moderate
acidity is still likely to be required, which would likely prove to be
uneconomic.
TABLE 1 REFERENCES
Biggs, M.S., 2023, Metallurgy Testing at ANSTO Started, unpublished memo for
Castillo Copper Limited, ROM Resources, Mar 2023,3pp.
Castillo Copper Limited, 2022a ASX Release, Drilling hits targeted cobalt
zones & wide pegmatite intercepts at Broken Hill 12 October 2022
Castillo Copper Limited, 2022b ASX Release, Drilling hits more wide pegmatite
intercepts at Broken Hill, 24 October 2022
Castillo Copper Limited, 2022c ASX Release, Completed auger sampling campaign
targets 6.5km2 REE mineralisation zone, 23 December 2022
Castillo Copper Limited, 2023a ASX Release, MREO focused metallurgical
test-work underway by ANSTO, 13 April 2023.
Datta, I., 2023, Technical memo, Scoping Tests for rare earth recovery,
prepared for Castillo Copper Limited, Jun23, 14pp.
Duuring, P 2020, Rare-element pegmatites: a mineral systems analysis:
Geological Survey of Western Australia, Record 2020/7, 6p.
Evenson, N. M., Hamilton, P. J. and O'Nions, R. K. (1978) "Rare Earth
Abundances in Chondrite Meteorites" Geochimica et Cosmochimica Acta 42,
1199-1212.
Kanazawa, Y.; Kamitani, M., 2006, "Rare earth minerals and resources in the
world". Journal of Alloys and Compounds. 408: 1339-1343.
doi:10.1016/j.jallcom.2005.04.033
Mohoney, M., 2018, BHA Broken Hill Project Position Paper, Squadron Resources
Pty Ltd., Unpublished report, Mar2018, 8pp.
Mortimer R., 2017, Re-interpretation of VTEM Profiles Broken Hill Area,
unpublished report by Southern Geoscience Consultants for Squadron Resources
Pty Ltd, Oct 17.
https://en.wikipedia.org/wiki/Regolith-hosted_rare_earth_element_deposits
Murakami, H.; Ishihara, S., 2008, REE mineralization of weathered crust and
clay sediment on granitic rocks in the Sanyo Belt, SW Japan and the Southern
Jiangxi Province, China". Resource Geology. 58 (4): 373-401.
doi:10.1111/j.1751-3928.2008.00071.x.
Willis, I.L., Brown, R.E., Stroud, W.J., Stevens, B.P.J., 1983, The Early
Proterozoic Willyama Supergroup: stratigraphic subdivision and interpretation
of high to low-grade metamorphic rocks in the Broken Hill Block, New South
Wales., Geological Society of Australia Journal, 30(2), p195-2
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