REE and Rb Soil Geochemistry Results at Arkun Project
Released
Released
Announcement PDF
ASX ANNOUNCEMENT
Date: 27 October 2021
EXTENSIVE RARE EARTH ELEMENTS AND RUBIDIUM
IN SOIL GEOCHEMISTRY RESULTS AT THE ARKUN PROJECT, WA
•
•
•
•
•
•
Numerous high priority targets for Rare Earth Elements (REE) and rubidium identified in
soil geochemistry data at the 1,900 sq km Arkun Project about 150 km east of Perth.
The soil anomalies occur over significant areas of many hundreds of metres along individual
reconnaissance soil geochemistry traverses.
The REE comprise both heavy and light rare earth elements including the valuable elements
neodymium, praseodymium, dysprosium, terbium, ytterbium, cerium and lanthanum.
No previous REE or rubidium exploration in the region.
Arkun increasingly recognised as a highly prospective part of the emerging mineral province
of SW Western Australia with the additional recent identification of significant targets for
nickel-copper-PGM mineralisation and lithium-caesium-tantalum (LCT) pegmatites,
Follow-up work including field checking and rock chip sampling is in progress. Land access
negotiations to commence as soon as practicable.
A significant number of high priority targets for Rare Earth Elements (REE) and rubidium have been
identified in recent soil geochemistry results from Impact Minerals Limited’s (ASX:IPT) 100% owned
Arkun project in the emerging mineral province of south west Western Australia (Figure 1).
Impact Minerals’ Managing Director Dr Mike Jones said “The Arkun Project continues to surprise us with
the recognition of numerous target areas for rare earth elements and rubidium. Although we were not
exploring for these commodities, one of Impact’s key target generation philosophies is to acquire large
strategic ground holdings in prospective regions and so it is not surprising that sometimes you might just
find what you weren’t looking for”.
“Although we do not yet know the true significance of the soil results, follow up work is definitely
warranted and we will do that as part of the follow up work on our recently identified targets for nickelcopper-PGM’s and LCT pegmatites in the same area. The extensive areas over which the REE and
rubidium occur suggest that drill targets may emerge with further work”.
Our work shows again how poorly explored this emerging mineral province of SW Western Australia
truly is and as demonstrated by the recent Julimar Ni-Cu-PGM discovery. It should also be remembered
that the province also hosts the Greenbushes lithium-tantalum mine which further attests to the potential
of this part of Western Australia to host world class deposits across a wide variety of commodity metals”
Dr Jones said.
26 Richardson Street West Perth Western Australia 6005
Tel +61 (8) 6454 6666 Facsimile +61 (8) 6454 6667
Email info@impactminerals.com.au www.impactminerals.com.au
Previous work by Impact identified 17 initial targets across the Arkun project area, principally for
Ni-Cu-PGM mineralisation (ASX Release 10th June 2021). Fifteen of these targets were covered by a
single soil geochemistry traverse up to several kilometres long along gazetted roads and tracks with
soil samples taken at 100 metre spacings along the traverses.
Each traverse was long enough to extend well away from the target area into areas of “background” in
order to establish the relative anomalism of the various metals in the target above background
The soil survey identified numerous priority targets for both Ni-Cu-PGE and, also unexpectedly,
lithium pegmatite mineralisation (refer to ASX Release 21st September 2021).
Further interpretation of the soil assay data has now also identified numerous target areas for REE and
rubidium mineralisation that warrant follow up work. The results are described below and are
presented as additive Z scores for REE in Figure 2 and as ppm values for rubidium in Figure 3. Further
details on some of the priority targets identified and the sampling and analytical techniques used are
presented at the end of the report, together with plots of the absolute values of some of the more
valuable REE for reference.
Figure 1. Location and Regional Geology of the Arkun Project, showing key nickel-copper-PGE
deposits and recent discoveries. Note the large tenement holdings of Anglo American Corporation
who applied for the ground on the same day of Impact’s first announcement about Arkun.
1. RARE EARTH ELEMENT RESULTS
The results for all 15 of the REE are shown as an additive Z score in Figure 2.
The REE comprise: lanthanum, cerium, praseodymium, neodymium, promethium, samarium,
europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.
It is evident that the central part of the Arkun project area stands out as being strongly anomalous in
the REE and six high priority targets and have been identified as warranting follow up work.
Numerous other areas of anomalism are also present.
Of note is that the targets are generally anomalous in both the light and the more valuable heavy REE
This is a very exciting outcome for Impact and supports the Company’s original contention that the
Arkun area is a highly prospective part of the Yilgarn Craton (Figure 2).
Three priority areas, R1 to R3 are shown in more detail in Figure 4 at the back of the report. The soil
anomalies all cover extensive areas and occur within larger magnetic granites.
R2
R3
R1
Figure 2. Additive Z scores for REE across the Arkun project. Note the large areas of anomalism in
the central part of the project area. Seven priority areas for follow up work are highlighted. Other areas
of elevated response are also evident.
2. RUBIDIUM
The results for rubidium are shown in Figure 3. Numerous areas stand out as being strongly
anomalous and four high priority targets have been identified for follow up work. Two of these areas,
Rb1 and Rb2, are shown in more detail in Figure 5 at the end of the report. Numerous other areas with
anomalous rubidium results are also evident (Figure 3).
Rb1
Rb2
Figure 3. Ionic leach results for rubidium. Four priority areas for follow up work are highlighted.
Other areas of elevated response are also evident. Note that the low absolute levels of rubidium are a
function of the very dilute nature of the chemical digest used in the Ionic Leach assay method.
3. DISCUSSION AND NEXT STEPS
The results of Impact’s first ever soil geochemistry programme at Arkun have outlined a significant
number of areas for follow up work for a wide range of commodities: nickel-copper-PGM; lithium
LCT pegmatites; REE and rubidium (ASX Release 21st September 2021).
Follow-up field checking and sampling will continue with the aim of prioritising areas for more
detailed soil geochemistry and ground geophysical surveys that will extend away from the roads and
into the surrounding paddocks.
In order to explore in the paddocks, land access agreements will be required with the relevant land
owners and this process will also be commenced. At present much of the region is under crop and
access too many of the targets for detailed follow up will be limited until after the harvest period later
in the year.
R1
R2
R3
Figure 4. Priority Targets for REE shown on images of regional magnetic data. Strongly elevated soil
geochemistry responses extend over distances of many hundreds of metres and are mainly associated
with the magnetic units with larger granite bodies.
Figure 5. Priority Targets for rubidium shown on images of regional magnetic data. Numerous areas
of strongly elevated values for rubidium above background are evident.
About the Soil Geochemistry Survey
The soil samples were submitted to ALS in Perth for analysis by the Ionic Leach method. This method
is a so-called “partial digest” technique that uses very dilute chemical solutions that only extract
weakly bound ions from the sample for analysis.
Many case studies have shown that partial digests tend to give better discrimination of soil
geochemical anomalies over background values. However, the weak nature of the chemical solutions
used means that the absolute values of metals returned in the analysis are much lower than those
returned from more aggressive digestion techniques such as aqua regia and four-acid digests. It is the
background-to-anomaly ratio that is the critical factor to consider.
Figure 6 shows the absolute values of the soil assays of the key REE for reference.
About Z Scores
Z scores are a standard statistical calculation of the number of standard deviations a raw data (assay)
value is from the mean of the data. For example a Z score of 2 indicates a value 2 standard deviations
above the mean. The higher the Z score, the more anomalous the data point is with respect to the
dataset.
Z scores are a standard method of normalising data so that statistically meaningful associations between
datasets can be made. In this case the Z scores for the individual elements that comprise the REE are
simply added together in order to amplify the metal associations.
Figure 6. Ionic Leach assays results for selected individual REE metals with maximum and minimum
values. The low values reflect the dilute nature of the digest used in the Ionic Leach method.
About the Arkun Project
The Arkun Project, which covers about 1,900 square kilometres, is centred between York and Corrigin
130 km east of Perth and was staked following the recent significant PGE discovery at Julimar just
75 km north east of Perth by Chalice Mining NL (Figures 1 and 7). Impact is now one of the larger
groundholders in the region (Figure 7).
Figure 7. Location of Impact’s Arkun project within the emerging Ni-Cu-PGM province of WA and
main tenement holders. Impact has one of the larger ground holdings in the region.
An interpretation of magnetic data by the Company identified a possible 500 km by 30 km mobile belt
that cuts through the Arkun project area. The belt is of a scale that suggests it may mark an ancient
terrane boundary or proto-craton margin. Such geological provinces (of varying ages) are well known
around the world as prospective terranes for hosting major nickel-copper-PGE deposits with examples
such as Nova-Bollinger and Mawson (Proterozoic age), the Thomson fold belt in Canada and the
recent discoveries at Yarawindah and Julimar in Western Australia.
Anglo American Corporation, one of the world’s leading mining companies lodged Exploration
Licence applications covering some 10,130 square kilometres surrounding three sides of the Arkun
project on the afternoon of 29th May 2020 a few hours after Impact made its first announcement on
Arkun (Figure 1 and ASX Release 10th June 2020).
COMPLIANCE STATEMENT
This report contains new Exploration Results for soil samples from the Arkun Project.
Dr Mike Jones
Managing Director
The review of exploration activities and results contained in this report is based on information compiled by Dr Mike Jones, a Member
of the Australian Institute of Geoscientists. He is a director of the company and works for Impact Minerals Limited. He has sufficient
experience which is relevant to the style of mineralisation and types of deposits under consideration and to the activity which he is
undertaking to qualify as a Competent Person as defined in the 2012 edition of the Australasian Code for Reporting of Exploration
Results, Mineral Resources and Ore Reserves (the JORC Code). Mike Jones has consented to the inclusion in the report of the matters
based on his information in the form and context in which it appears.
APPENDIX 1 - SECTION 1 SAMPLING TECHNIQUES AND DATA
Criteria
Sampling techniques
Drilling techniques
Drill sample recovery
Logging
JORC Code explanation
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.
Commentary
Soil samples of a weight of about 250 grams were taken from a depth of about 15-20 cm below surface.
They were sieved on site to -2 mm and placed in plastic snap seal bags for transport to the laboratory.
Include reference to measures taken to ensure sample representivity and
the appropriate calibration of any measurement tools or systems used
The soil samples were taken on 100 metre spacings along gazetted roads and tracks across 15 priority
targets. Although there is only one line of samples per target area enough samples were taken to
establish the background values of the metals and elements that can be used to determine levels of
anomalism.
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 30 g
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 (e.g. submarine nodules)
may warrant disclosure of detailed information
The soil samples were taken using industry standard procedures.
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).
N/A
Method of recording and assessing core and chip sample recoveries and
results assessed
N/A
Measures taken to maximise sample recovery and ensure representative
nature of the samples
Standard field procedures for soil samples were used.
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.
No sample bias has been established.
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.
N/A
Criteria
Sub-sampling techniques and
sample preparation
Quality of assay data and
laboratory tests
Verification of sampling and
assaying
JORC Code explanation
Commentary
Whether logging is qualitative or quantitative in nature. Core (or costean,
channel, etc) photography.
N/A
The total length and percentage of the relevant intersections logged
N/A
If core, whether cut or sawn and whether quarter, half or all core taken.
N/A
If non-core, whether riffled, tube sampled, rotary split, etc and whether
sampled wet or dry.
N/A
For all sample types, the nature, quality and appropriateness of the sample
preparation technique.
The size and distribution of the soil samples is appropriate for regional exploration.
Quality control procedures adopted for all sub-sampling stages to
maximise representivity of samples.
Laboratory QC procedures for soil samples involve the use of internal certified reference material as
assay standards, along with blanks, duplicates and replicates.
Measures taken to ensure that the sampling is representative of the in situ
material collected, including for instance results for field duplicate/secondhalf sampling.
No field duplicates were taken as this is not warranted at this early stage of exploration.
Whether sample sizes are appropriate to the grain size of the material
being sampled.
Sample sizes are appropriate
The nature, quality and appropriateness of the assaying and laboratory
procedures used and whether the technique is considered partial or total.
Samples were submitted to ALS Laboratories in Perth for analysis by the ionic leach method ME-MS23
with ICP-MS finish for 61 elements including: Ag, Au, Bi, Cd, Co, Cr, Cs, Cu, Li, Mo, Ni, Pb, Pd, Pt, Sn, Ta,
W, Zn and REE Ce, La, Tb, Dy, Pm, Pr, Nd, Sm, Gd, Eu, Ho, Er, Tm, Lu, Yb and Rb. Sample preparation
involved weighing out of 50 g of the soil sample and adding a fixed aliquot of the digest.
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.
N/A
Nature of quality control procedures adopted (e.g. standards, blanks,
duplicates, external laboratory checks) and whether acceptable levels of
accuracy (i.e. lack of bias) and precision have been established.
Duplicate samples are not required at this early stage of exploration.
The verification of significant intersections by either independent or
alternative company personnel.
The results have not been verified by independent or alternative companies. This is not required at this
stage of exploration.
The use of twinned holes.
N/A
Documentation of primary data, data entry procedures, data verification,
data storage (physical and electronic) protocols.
Primary assay data has been entered into standard Excel templates for plotting in QGIS and IOGAS.
Discuss any adjustment to assay data.
There are no adjustments to the assay data.
Criteria
Location of data points
JORC Code explanation
Accuracy and quality of surveys used to locate drill holes (collar and downhole surveys), trenches, mine workings and other locations used in Mineral
Resource estimation.
Commentary
Sample locations were located by hand held GPS.
Specification of the grid system used.
The grid system for ARKUN is MGA_GDA94, Zone 50.
Quality and adequacy of topographic control.
N/A
Data spacing for reporting of Exploration Results.
The samples were taken at 100 metre spacings along the traverses.
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.
N/A
Whether sample compositing has been applied.
N/A
Whether the orientation of sampling achieves unbiased sampling of
possible structures and the extent to which this is known, considering the
deposit type.
Not relevant to soil results.
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.
Not relevant to soil results.
Sample security
The measures taken to ensure sample security.
Samples were taken by Impact contractors and delivered by them directly to the laboratory.
Audits or reviews
The results of any audits or reviews of sampling techniques and data.
At this stage of exploration a review of the sampling techniques and data by an external party is not
warranted.
Data spacing and distribution
Orientation of data in relation
to geological structure
SECTION 2 REPORTING OF EXPLORATION RESULTS
Criteria
Mineral tenement and land
tenure status
Exploration done by other
parties
JORC Code explanation
Commentary
Type, reference name/number, location and ownership including
agreements or material issues with third parties such as joint ventures,
partnerships, overriding royalties, native title interests, historical sites,
wilderness or national park and environmental settings.
The Arkun Project currently comprises 7 exploration licences covering about 1,900 km2. The tenements
are held 100% by Aurigen Pty Ltd a 100% owned subsidiary of Impact Minerals Limited. Impact has
signed Land Access agreements in place with the various Native Title claimants that cover the area.
The security of the tenure held at the time of reporting along with any
known impediments to obtaining a licence to operate in the area.
The tenements are in good standing with no known impediments.
Acknowledgment and appraisal of exploration by other parties.
There has been no significant previous work at this project.
Criteria
Geology
Drill hole Information
Data aggregation methods
JORC Code explanation
Commentary
Deposit type, geological setting and style of mineralisation.
Nickel-copper-PGE sulphide mineralisation associated with mafic to ultramafic intrusions and goldcopper in deformed and metamorphosed greenstone belts.
A summary of all information material to the understanding of the
exploration results including a tabulation of the following information for
all Material drill holes:
•
easting and northing of the drill hole collar
•
elevation or RL (Reduced Level – elevation above sea level in
metres) of the drill hole collar
•
dip and azimuth of the hole
•
down hole length and interception depth
•
hole length.
N/A
In reporting Exploration Results, weighting averaging techniques,
maximum and/or minimum grade truncations (e.g. cutting of high grades)
and cut-off grades are usually Material and should be stated.
N/A.
Where aggregate intercepts incorporate short lengths of high grade
results and longer lengths of low grade results, the procedure used for
such aggregation should be stated and some typical examples of such
aggregations should be shown in detail.
N/A
The assumptions used for any reporting of metal equivalent values should
be clearly stated.
N/A
Relationship between
mineralisation widths and
intercept lengths
These relationships are particularly important in the reporting of
Exploration Results.
If the geometry of the mineralisation with respect to the drill hole angle is
known, its nature should be reported.
If it is not known and only the down hole lengths are reported, there
should 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
should be included for any significant discovery being reported These
should include, but not be limited to a plan view of drill hole collar
locations and appropriate sectional views.
Refer to Figures in body of text.
Where comprehensive reporting of all Exploration Results is not
practicable, representative reporting of both low and high grades and/or
widths should be practiced to avoid misleading reporting of Exploration
Results.
All results reported are representative
Balanced reporting
N/A
Criteria
JORC Code explanation
Other substantive exploration
data
Other exploration data, if meaningful and material, should be reported
including (but not limited to): geological observations; geophysical survey
results; geochemical survey results; bulk samples – size and method of
treatment; metallurgical test results; bulk density, groundwater,
geotechnical and rock characteristics; potential deleterious or
contaminating substances.
Further work
The nature and scale of planned further work (e.g. tests for lateral
extensions or depth extensions or large-scale step-out drilling).
Diagrams clearly highlighting the areas of possible extensions, including
the main geological interpretations and future drilling areas, provided this
information is not commercially sensitive
Commentary
Assessment of other substantive exploration data is not yet complete however considered immaterial at
this stage.
Follow-up work programmes will be subject to interpretation of results which is ongoing.
Share your feedback
Discover