Nature and quality of sampling (e.g., cut channels, random chips, or specific specialised industry standard measurement tools appropriate to the minerals under investigation, such as down hole gamma sondes, or handheld XRF instruments, etc.). These examples should not be taken as limiting the broad meaning of sampling.

Include reference to measures taken to ensure sample representivity and the appropriate calibration of any measurement tools or systems used.

Aspects of the determination of mineralisation that are Material to the Public Report.

In cases where 'industry standard' work has been done this would be relatively simple (e.g., 'reverse circulation drilling was used to obtain 1 m samples 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 gold that has inherent sampling problems. Unusual commodities or mineralisation types (eg submarine nodules) may warrant disclosure of detailed information.

Diamond Drilling (DDH)

Diamond drilling of HQ diameter (TT_005DD) was completed to 137.7m recently in the completed program and was located 5m away from a RC hole already drilled (TT_003RC).

Reverse Circulation ('RC') Drilling

RC drilling at Fence Gossan was used to obtain a representative sample by means of riffle splitting with samples submitted for analysis using the above-mentioned methodologies.

Four (4) reverse circulation (RC) holes for a total of 516m have been completed at the Fence Gossan Prospect.

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).

Drill type (e.g., core, reverse circulation, open-hole hammer, rotary air blast, auger, Bangka, sonic, etc.) and details (e.g. core diameter, triple or standard tube, depth of diamond tails, face-sampling bit or other type, whether core is oriented and if so, by what method, etc.).

Historical drilling consisted of auger, rotary air blast, reverse circulation, and NQ, BQ, and HQ diamond coring.  One cored hole of HQ (61mm) diameter was completed at Tors Tank after all the RC holes had been completed.

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).

Method of recording and assessing core and chip sample recoveries and results assessed.

Measures taken to maximise sample recovery and ensure representative nature of the samples.

Whether a relationship exists between sample recovery and grade and whether sample bias may have occurred due to preferential loss/gain of fine/coarse material.

Reverse Circulation ('RC') Drilling - Reverse circulation sample recoveries were visually estimated during drilling programs. Where the estimated sample recovery was below 100% this was recorded in field logs by means of qualitative observation.

Reverse circulation drilling employed sufficient air (using a compressor and booster) to maximise sample recovery.

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.

Whether core and chip samples have been geologically and geotechnically logged to a level of detail to support appropriate Mineral Resource estimation, mining studies and metallurgical studies.

Whether logging is qualitative or quantitative in nature. Core (or costean, channel, etc) photography.

The total length and percentage of the relevant intersections logged.

The drilling that did occur was completed to modern-day standards. The preferred exploration strategy in the eighties and early nineties was to drill shallow auger holes to negate the influence of any Quaternary and Tertiary sedimentary cover, and then return to sites where anomalous Cu or Zn were assayed.  In this program at all three areas holes were completed to varying depths ranging from 100-160m.

No downhole geophysical logging took place; however, measurements of magnetic susceptibility were taken at the same 1m intervals as the PXRF readings were taken.

If core, whether cut or sawn and whether quarter, half or all core taken.

If non-core, whether riffled, tube sampled, rotary split, etc and whether sampled wet or dry.

For all sample types, the nature, quality, and appropriateness of the sample preparation technique.

Quality control procedures adopted for all sub-sampling stages to maximise representivity of samples.

Measures taken to ensure that the sampling is representative of the in-situ material collected, including for instance results for field duplicate/second-half sampling.

Whether sample sizes are appropriate to the grain size of the material being sampled.

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 variation of sample ratios noted are considered consistent with the sub-sampling technique (hand-splitting).

No second half samples will be submitted for analysis, but duplicates have been taken at a frequency of 1:20 in samples collected.

It is considered water planned to be used for core cutting is unprocessed and unlikely to have introduced sample contamination.

Procedures relating to the definition of the line of cutting or splitting are not available.  It is expected that 'standard industry practice' for the period was applied to maximize sample representivity.

Quarter core will be submitted to ALS for chemical analysis using industry 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, d, e, f).

The nature, quality and appropriateness of the assaying and laboratory procedures used and whether the technique is considered partial or total.

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.

Nature of quality control procedures adopted (eg standards, blanks, duplicates, external laboratory checks) and whether acceptable levels of accuracy (i.e. lack of bias) and precision have been established.

Laboratory inserted standards, blanks and duplicates were analysed per industry standard practice.  There was no evidence of bias from these results.

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.

·      None of the drillholes have been twinned, as they are historical holes.

·      Conversion of elemental analysis (REE parts per million) to stoichiometric oxide (REO parts per million) was undertaken by ROM geological staff using the below (Table D1-1) element to stoichiometric oxide conversion factors (https://www.jcu.edu.au/news/releases/2020/march/rare-earth-metals-an-untapped-resource)

Table D1-1:  Element -Conversion Factor -Oxide Form

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) = La2O3 + CeO2 + Pr6O11 + Nd2O3 + Sm2O3 + Eu2O3 + Gd2O3 + Tb4O7 + Dy2O3 + Ho2O3 + Er2O3 + Tm2O3 + Yb2O3 + Y2O3 + Lu2O3.

TREO-Ce = TREO - CeO2

LREO (Light Rare Earth Oxide) = La2O3 + CeO2 + Pr6O11 + Nd2O3 + Sm2O3 

HREO (Heavy Rare Earth Oxide) = Eu2O3 + Gd2O3 + Tb4O7 + Dy2O3 + Ho2O3 + Er2O3 + Tm2O3 + Yb2O3 + Y2O3 + Lu2O3

CREO (Critical Rare Earth Oxide) = Nd2O3 + Eu2O3 + Tb4O7 + Dy2O3 + Y2O3

MREO (Magnetic Rare Earth Oxide) = Pr6O11 + Nd2O3 + Sm2O3 + Gd2O3 + Tb4O7 + Dy2O3.

Total Rare Earth Oxides (TREO):

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 = La₂O₃

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.

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.

In general, locational accuracy does vary, depending upon whether the historical surface and drillhole samples were digitised off plans or had their coordinated tabulated.  Many samples were originally reported to AGD66 or AMG84 and have been converted to MGA94 (Zone 54)

The holes are currently surveyed with handheld GPS, awaiting more accurate DGPS survey.  It is thus estimated that locational accuracy therefore varies between 2-4m until the more accurate surveying is completed.  This assessment was confirmed once the holes were surveyed by DGPS from GMC Surveying.

The quality of topographic control (GSNSW 1 sec DEM) is deemed adequate for the purposes of the exploration drilling program.

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 D1-2, below:

Table D1-2:  EL 8434 Drillhole Spacing

The Datamine software allows creation of fixed length samples from the original database given a set of stringent rules.

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 (Figure D1-3 and D1-4).

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.

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.

The Company considers that risks associated with sample security are limited given the nature of the targeted mineralisation.

The results of any audits or reviews of sampling techniques and data.

No external audits or reviews have yet been undertaken.

EL 8434 is located about 28km east of Broken Hill whilst EL 8435 is 16km east of Broken Hill.  Both tenures are approximately 900km northwest of Sydney in far western New South Wales (Figures D2-1 and D2-2 in Appendix A &B, above). 

EL 8434 and EL 8435 were both granted on the 2^{nd of} June 2016 to Squadron Resources for a term of five (5) years for Group One Minerals.  On the 25^{th 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 580km².

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 68km².

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 the 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 D2-1).

Figure D2-1:  EL 8434 and EL 8435 General Location Map

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.  Depth of 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 subcrops 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 dominantly 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 data base.  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.

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 D2-2: Weathering Profile over REE - Rich Granite

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 (PO₄)) 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. 

Header information about all drillholes completed at Reefs Tank, Tors Tank and Fence Gossan have been tabulated in this release in Appendix C.

No metal equivalents have been reported.  Rare earth element results have been converted to rare earth oxides as per standard industry practice (Castillo Copper 2022f).

No compositing of assay results has taken place, but rather menu options within the Datamine GDB module have been used to create fixed length 1m assay intervals from the original sampling lengths.

The rules follow very similarly to those used by the Leapfrog Geo software in creating fixed length samples.

A database of all the historical borehole sampling has been compiled and validated. It is uncertain if there is a strong relationship between the surface sample anomalies to any subsurface anomalous intersections due to the possible masking by variable Quaternary and Tertiary overburden that varies in depth from 0-15m.  The mineralisation appears to be secondary enrichment in the regolith clays and extremely weathered material derived from quartzo-feldspathic pegmatites.  

Current surface anomalies are shown on maps released on the ASX (Castillo Copper 2022d, 2022e, 2022f and 2022g).  All historical surface sampling has had their coordinates converted to MGA94, Zone 54.

All recent laboratory analytical results have been recently reported (see Castillo Copper 2022a, b, c, d, e, f, and g) for assay results.

Regarding the surface and sampling, no results other than duplicates, blanks or reference standard assays have been omitted.

Historical explorers have also conducted airborne and ground gravity, magnetic, EM, and IP resistivity surveys over parts of the tenure area but this is yet to be fully georeferenced (especially the ground IP surveys). Squadron Resources conducted an airborne EM survey in 2017 that covers Iron Blow and The Sisters, but not the southern cobalt and REE prospects.

REFERENCES

Biggs, M. S., 2021a, Broken Hill Alliance, NSW Tenure Package Background Geological Information, unpublished report to BH Alliance Pty Ltd, Sep 21, 30pp.

Biggs, M. S., 2021b, EL 8434 and EL 8435, Brief Review of Surface Sample Anomalies Lithium, Rare Earth Elements and Cobalt, unpublished report to BH Alliance Pty Ltd, Nov 21, 18pp.

Biggs, M.S., 2022a, BHA Cobalt Modelling and Mineral Resource Estimate Update, unpublished memo for Castillo Copper by ROM Resources.

Biggs, M.S., 2022b, Broken Hill BHA Tenures Update, Castillo Copper, unpublished memo prepared by ROM Resources, Mar 22, 5pp

Biggs M.S., 2022c, Geological Briefing Paper, Iron Blow Prospect, East Zone, BHA Project (BHAE), Broken Hill, NSW, ROM Resources, prepared for Castillo Copper Limited, August 2022

Burkett R.D., 1975, Progress Report on Exploration Licenses 780, 781, 782 and 783, Broken Hill Area, NSW for the six months to 23rd November 1975, North Broken Hill Limited for the NSW Geological Survey, (GS1975-328)

Castillo Copper Limited, 2020, ASX Release Acquisition enhances BHT (zinc-silver-lead) and IOCG (gold-copper) prospectivity at Broken Hill, 1st October 2020.

Castillo Copper Limited, 2022a, ASX Release Battery metal drill-hole assays unlock BHA East Zone potential / lithium update, 5th January 2022.

Castillo Copper Limited, 2022b, ASX Release Strategic focus to develop significant cobalt mineralisation potential at BHA Project, 9th February 2022.

Castillo Copper Limited, 2022c, ASX Release High grade platinum confirmed at BHA Project, 9th March 2022.

Castillo Copper Limited, 2022d ASX Release Diamond core tests demonstrate high-grade cobalt-zinc potential at Broken Hill, 21 March 2022

Castillo Copper Limited, 2022e ASX Release, Drilling hits targeted cobalt zones & wide pegmatite intercepts at Broken Hill 12 October 2022

Castillo Copper Limited, 2022f ASX Release, Drilling hits more wide pegmatite intercepts at Broken Hill, 24 October 2022

Castillo Copper Limited, 2022g ASX Release, Completed auger sampling campaign targets 6.5km² REE mineralisation zone, 23 December 2022

Duuring, P 2020, Rare-element pegmatites: a mineral systems analysis: Geological Survey of Western Australia, Record 2020/7, 6p.

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

Lees, T.C., 1978, Progress Report on Farmcote Exploration Licenses 780 and 782, Farmcote Area, Broken Hill, NSW for the six months to 23RD November 1978, North Broken Hill Limited for the NSW Geological Survey, (GS1978-043)

Leyh, W.R., 1976, Progress Report on Exploration Licence, No. 846 Iron Blow -Yellowstone Area, Broken Hill, New South Wales for the six months period ended 29th June 1976, North Broken Hill Limited, Report GS1976-198, Jul 76, 88pp

Leyh, W.R., 1977a, Progress Report on Exploration Licence, No. 846 Iron Blow -Yellowstone Area, Broken Hill, New South Wales for the six months period ended 29th December 1976, North Broken Hill Limited, Report GS1976-198, Feb 1977, 24pp

Leyh W.R., 1977b, Progress Report on Farmcote Exploration Licenses 780 and 782, Farmcote Area, Broken Hill, NSW for the three months to 5th March 1977, North Broken Hill Limited for the NSW Geological Survey, (GS1977-078)

Leyh W.R., 1977c, Progress Report on Farmcote Exploration Licenses 780 and 782, Farmcote Area, Broken Hill, NSW for the three months to 23rd May 1977, North Broken Hill Limited for the NSW Geological Survey, (GS1977-078)

Leyh W.R., 1978, Progress Report on Farmcote Exploration Licenses 780 and 782, Farmcote Area, Broken Hill, NSW for the three months to 27 October 1978, North Broken Hill Limited for the NSW Geological Survey, (GS1977-078)

Leyh W.R., 1978 Progress Report on Exploration Licenses 1099 and 1100 for the six months to 27 October 1978, North Broken Hill Limited for the NSW Geological Survey, (GS1978-407)

Leyh, W.R., 1990, Exploration Report for the Third Six Monthly Period ended 12th June 1990 for EL 3238 (K Tank), Broken Hill District, New South Wales for the six months period, Pasminco Limited, Report GS1989-226, Jun 90, 22pp

Leyh, W.R., and Lees T.C., 1977, Progress Report on Exploration Licence, No. 846 Iron Blow -Yellowstone Area, Broken Hill, New South Wales for the six months period ended 29th June 1977, North Broken Hill Limited, Report GS1976-198, Jul 77, 35pp

Leyh, W.R., and Larson P.D., 1981, Final Report for the Third Six Monthly Period ended 12th June 1990 for EL 3238 (K Tank), Broken Hill District, New South Wales for the six months period, Pasminco Limited, Report GS1989-226, Jun 90, 22pp

McConachie, G.W., 1997, EL 4792 Redan, Annual Report for the period ending 19/2/1997, Normandy Exploration Limited, unpublished report to the GSNSW, RIN 00002672

Main, J.V., and Tucker D.F., 1981, Exploration Report for Six Month Period 8th November 1980 to 7th May 1981, EL 1106 Rockwell, Broken Hill, NSW, CRA Exploration Pty Ltd, GS1980-080, Jul 1981, 40pp

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.

Segnit, E.R. (1946) Barium-feldspars from Broken Hill, New South Wales. Mineralogical Magazine, 27, 166-174.

Squadron Resources Pty Ltd, 2018, Broken Hill Project Status, August 2018, unpublished confidential presentation by Squadron Resources,

Timms, P.D., and Groves A.J., 2003, Exploration Licence 4846, The Sisters, Annual Report to 29th May 2003, Endeavour Minerals Pty Ltd., RIN

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