Antucoya West drill results confirm mineralised system
Released
Released
Announcement PDF
Chile’s star in copper-gold
ESTRELLA RESOURCES LIMITED
ACN 151 155 207
AUSTRALIAN REGISTERED OFFICE:
Level 51 MLC Centre 19-29 Martin Place
Sydney NSW 2000 Australia
Email: admin@estrellaresources.com.au
CHILE OFFICE:
Santa Beatriz 294
Providencia, Santiago, Chile
ASX ANNOUNCEMENT
05 August 2014
Antucoya West drill results confirm
mineralised system adjacent to Antucoya
Mine Development
HIGHLIGHTS
ASX CODE: ESR
Assay results identify significant mineralised copper system within 2km of
Antofagasta’s Antucoya mine development.
Copper mineralisation found within the Buey Muerto Fault Zone as it extends
beyond Antucoya.
For further information please contact:
Mineralisation commences near-surface.
Mineralisation coincident with electrical resistivity dipoles: several more targets
remain untested.
Dr. Jason Berton MAusIMM
Managing Director
Contact Details:
Email: admin@estrellaresources.com.au
1.
Introduction
Estrella Resources (ASX: ESR, Estrella or the Company) is pleased to advise that it
has received assay results from the initial 38 Reverse Circulation (RC) holes at the
Antucoya West Prospect. Estrella’s Antucoya West Prospect lies immediately west of
Antofagasta Minerals PLC’s (LON:ANTO) Antucoya mine development.
Figure 1: Project Altair locality map, Region II, northern Chile.
www.estrellaresources.com.au
AUSTRALIA | CHILE
ASX ANNOUNCEMENT
2.
Antucoya West drilling results
Estrella’s initial drilling campaign at the Antucoya West project has returned significant assays from 11 shallow drill
holes which have identified two main zones of mineralisation in;
i.
ii.
the southeast sector;
the northeast sector;
Southeast Sector - the southeast sector consists of a cluster of 6 mineralised intercepts that range from 0.1% to 0.15%
Cu with associated anomalous molybdenum values (9 to 39 ppm) (see Figure 2, Figure 3 and Table 1). In the context of
porphyry copper-molybdenum emplacement Estrella believes that this mineralisation represents the top of a significant
ore body.
The RC drill program consisted of widely spaced (250-500 metres apart), shallow drill holes (mostly 20 metres depth)
targeted to penetrate the cover ‘caliche’ gravels in order to identify and sample the bedrock unit for copper
2
mineralisation over a 7 km area (ASX announcement 26 May 2014). All assay samples were taken over 2 metre
intervals to minimise exploration costs. Estrella considers assay results for copper above 500 ppm to be anomalous and
above 750 ppm to be significant in terms of detecting a mineralised system.
The identified mineralisation is spatially coincident with observed jarosite alteration. Jarosite is commonly associated
with ore bodies as it is a mineral formed by the oxidation of iron sulphides (for example pyrite) often associated with
copper mineralisation. Hydrothermal texture pyrite has been observed frequently in the rock chip cuttings throughout
this sector.
The geology in the southeast sector features copper mineralisation within younger (likely Early Cretaceous) intrusive
diorite rocks and extrusive rhyodacite rocks emplaced within the surrounding older Jurassic volcanic rocks (La Negra
Formation - LNF). Structurally the rocks all lie within the Buey Muerto Fault Zone (BMZ). The nearby Antucoya Mine
Development Project (owned by Antofagasta Minerals PLC) is a porphyry copper type deposit consisting of intrusive
Early Cretaceous granodiorite and tonalite rocks, also positioned within the BMZ and surrounded by older Jurassic
volcanic rocks (LNF) (refer Maksaev et. al, 2006). Estrella is excited by the possibility that the copper mineralisation at
its Antucoya West Prospect is within a similar geological setting to mineralisation at Antofagasta’s Antucoya deposit.
In summary, the observations that support the existence of a porphyry copper type mineralised system at Antucoya
West include:
Proximity to fault structures of the BMZ;
Post-Jurassic instrusive rocks;
Copper mineralisation (commencing at surface);
Jarosite alteration (formed by oxidation of iron sulphides and commonly associated with ore bodies) and
hydrothermal pyrite;
Fault breccia units (fault related volcanic breccias with silica and tourmaline);
Anomalous Molybdenum assay results (RCAW004, RCAW016 & RCAW021);
Electrical resistivity dipole zones; and
Close proximity to Antofagasta’s Antucoya porphyry deposit.
Northeast Sector - Estrella drilled significantly deeper holes of up to 50 metres in the northeast sector due to thicker
‘caliche’ gravel cover. Once the bedrock was intersected the holes were only continued a maximum of a further 10
metres to identify the rock type and detect copper mineralisation. Hole RCAW-036 identified significant copper
mineralisation (0.15% Cu from 40-48 metres) hosted within porphyritic dacite rocks. More information from deeper
drilling is required in this zone to test for nearby intrusive source rocks to the mineralisation.
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AUSTRALIA | CHILE
ASX ANNOUNCEMENT
Figure 2: Antucoya West geology map with the best drill hole intercepts from the 38 hole detection program (Map
Datum WGS84 Zn19s). The yellow ellipse highlights the mineralised cluster identified by the shallow RC drill program.
Several targets remain untested to the east of the drilled area in the recent shallow RC program. Estrella considers the
strong dipole zone east of the prospective southeast sector to be a high priority zone that will be tested during follow
up drilling campaigns.
AUSTRALIA | CHILE
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ASX ANNOUNCEMENT
Figure 3: Antucoya West drilling results and geology map overlaid on the electrical resistivity image (Map Datum
WGS84 Zn19s).
AUSTRALIA | CHILE
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ASX ANNOUNCEMENT
Table 1: Summary of significant drilling results for Antucoya West shallow RC holes.
Easting
Northing
Hole ID
From
To
Cu ppm
Cu interval Mo ppm
406236
7499067
RCAW001
14
16
513
405506
7498008
RCAW004
14
16
501
16
18
962
6m @
27
18
20
810
758
39
9
405506
7500002
RCAW010
16
18
566
406502
7500503
RCAW014
14
16
675
4m @
16
18
674
675
28
30
978
30
32
1080
32
34
573
13
34
36
1075
11
36
38
838
12m @
11
38
40
1060
934
10
405003
7500751
RCAW016
Base Of
End of
Rock type
Cover (m) Hole (m)
0
24
8
20
Diorite
12
18
10
18
RCAW018
18
20
648
20
20
405039
7498755
RCAW019
0
2
661
0
20
2
4
421
4
6
457
6
8
675
8
10
615
10
12
1030
12
14
1285
4m @
14
16
1750
1518
2
4
1910
4m @
4
6
1170
1540
12
14
599
14
16
518
16
18
873
18
20
1455
405498
406500
7498499
7498246
RCAW021
RCAW022
RCAW025
Andesite
Diorite
7501255
7498750
Diorite
48
406482
405973
Breccia
Gravel
Diorite
12
10
20
0
20
8
20
Breccia
Andesite
Diorite
405520
7501233
RCAW030
4
6
537
2
20
406002
7502751
RCAW036
40
42
2300
32
50
42
44
1025
44
46
1655
46
48
914
10m @
48
50
591
1297
Andesite
Dacite porphyritic
(Drill hole coordinates; WGS84, Zn19S).
AUSTRALIA | CHILE
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ASX ANNOUNCEMENT
3.
Follow up exploration activity
Estrella is waiting for the remaining assays from the shallow holes drilled at the Colupo and Colupo Norte prospects
(20km to the north of Antocuyo West) prior to recommencing drilling activity in Altair. Assays are due in the next 7 days
and results will be announced to the market once the information has been received, compiled and collated.
As stated in its Quarterly Activities Report, “Estrella is currently finalising the Quality Assessment – Quality Control (QAQC) measures to produce a JORC 2012 compliant Mineral Resource for Colupo. Estrella has now engaged a Competent
Person who is scheduled for a site visit in August for this purpose and the compilation of a resource estimation and
statement will follow. Subject to the outcome of the initial resource estimation, Estrella will be able to consider future
production scenarios at Colupo.”
4.
The Altair Project
Estrella’s Altair Project encompasses 112,366 ha in the Coastal Belt, Region II of northern Chile (see Figure 3) and
features several active exploration prospects; Antucoya West, Colupo, Dania, Ivannia and Colupo Norte. Estrella holds
the Altair Project under two Option Agreements with SQM (NYSE:SQM). The Coastal Belt in this region is emerging as a
significant mining district in Chile with new mines being developed (for example the Antofagasta Minerals owned
Antucoya Project referred to in this announcement) and several long standing mines (AngloAmerican owned Mantos
Blancos and the Antofagasta Minerals owned Michilla mine) as well as SQM’s nitrate operations. Significant
infrastructure including ports, power, rail, water pipeline and roads already exist in the region (see Figure 3 and Figure
4). See Table 2 for reported Ore Reserves and Mineral Resources for Antucoya, Michilla and Mantos Blancos mines
(None Estrella owned).
AUSTRALIA | CHILE
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ASX ANNOUNCEMENT
Figure 4: Locality map of Estrella’s active exploration prospects within Altair and its proximity to nearby mining
infrastructure (not owned by Estrella) (Map Datum WGS84 Zn19S).
In total SQM drilled 77 holes across the Ivannia, Dania and Colupo prospects between 2007 and 2011. Since then
Estrella has drilled at Colupo, 9 conventional RC holes (refer ASX announcements of 11 November and 3 December
2013), 21 shallow RC holes, and 3 Diamond drill holes (refer ASX announcement of 18 March 2014)), Colupo Norte (4
shallow RC holes), Dania (two Diamond drill holes (refer ASX announcements of 7 April and 29 April 2014)), Antucoya
West (38 shallow RC holes). Assay results are pending for the shallow RC holes at Colupo and Colupo Norte. Additional
to the Option Agreement with SQM, Estrella also holds 100% tenure for 10,867 ha.
AUSTRALIA | CHILE
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ASX ANNOUNCEMENT
Table 2: Mines and project developments nearby to Project Altair (None owned by Estrella)
Nearby Deposits *
Ore Reserve
Mineral Resource
Mineralisation style
Proximity to Altair
( All not owned by Estrella)
Measured: 26.7Mt @ 1.61%
Michilla
N/A
Indicated: 24.7Mt @ 1.45%
Manto & Breccias
17 km west of
Saturno
Inferred: 15.8Mt @ 1.67%
Proven: 215Mt @ 0.38%
Antucoya
Measured:278 Mt @ 0.34%
Indicated:737 Mt @ 0.30%
Porphyry
Probable: 427Mt @ 0.34%
Surrounded by
Altair
Inferred:91 Mt @ 0.28%
Mantos Blancos
Proven: 26.3 Mt @ 0.83%, 8.3
Measured:47.8 Mt @ 0.75%, 14.1Mt @
Mt @ 0.54%, 2.1Mt @ 0.18%
0.47%
Indicated: 68.1 Mt @ 0.56%, 10.5 Mt @
Probable: 19.7 Mt @ 0.80%,
0.43%, 8.3 Mt @ 0.20%
Rhyolite dome
40 km south of
Altair
16.3 Mt @ 0.33%, 49.6Mt @
0.23%
Inferred: 30.5 Mt @ 0.55%, 5.2Mt @
0.49%
Disclaimer: This table and information contained therein relates to nearby deposits of Project Altair, none of which are owned by Estrella. The
information is obtained from publicly available information. All deposits have been published in compliance with the 2004 JORC Code. Estrella makes
no comparison between its projects and these named deposits other than to demonstrate their locality. There is no guarantee that Estrella’s projects
will realise similar results.
Competent Person’s Statement
Exploration information in this announcement is based upon and fairly represents, information, supporting documentation and work undertaken by
Dr. Jason Berton, the Managing Director and a full-time employee of Estrella Resources Limited whom is a Member of the Australasian Institute of
Metallurgy and Mining (AusIMM). Dr Berton has sufficient experience that is relevant to the style of mineralisation and type of deposit 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’ (JORC Code). Dr Berton consents to the inclusion in this presentation of the
statements based on his information and context in which they appear.
About Estrella Resources
Directors and Management
Estrella Resources Limited is an ASX listed, Chilean focused
copper-gold exploration company. Estrella has a number of
exploration projects in Chile. With a highly experienced board, a
strong operational and management team and a sole focus on
Chilean copper and gold projects, the Company is well positioned
to develop its projects and add value for shareholders.
Independent Non-Executive
Chairman:
-Robert Thomson
Independent Non-Executive
Director:
-Julian Bavin
ESTRELLA RESOURCES LIMITED
ACN 151 155 207
ASX CODE: ESR
ORDINARY FULLY PAID SHARES:
108,278,728
UNLISTED OPTIONS:
12,380,000
Managing Director
-Dr. Jason Berton
Company Secretary
-Justin Clyne
AUSTRALIA | CHILE
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ASX ANNOUNCEMENT
JORC Code, 2012 Edition – Table 1 report template
Section 1 Sampling Techniques and Data
(Criteria in this section apply to all succeeding sections.)
Criteria
JORC Code explanation
Commentary
Sampling
techniques
Drilling
techniques
Nature and quality of sampling (eg 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 (eg
‘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 (eg
submarine nodules) may warrant disclosure
of detailed information.
Drill type (eg core, reverse circulation, openhole hammer, rotary air blast, auger, Bangka,
sonic, etc) and details (eg 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).
Drill sample
recovery
Logging
AUSTRALIA | CHILE
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.
Whether core and chip samples have been
geologically and geotechnical logged to a
level of detail to support appropriate Mineral
Resource estimation, mining studies and
metallurgical studies.
Whether logging is qualitative or quantitative
Sample recoveries for reverse circulation were
systematically recorded. The sampling of RC drilling
cuttings was undertaken at intervals of two meter by
reduction of the drill cuttings with a Jones riffle splitter
to provide approximately 60kg of RC cuttings per 2m
interval. Approximately 20kg of <10# coarse reject
material is stored on site for reference.
The sampling procedures included two reduction of
the drill cutting with the Jones riffle splitter for the
sample to be analyzed and for the duplicate, the ticket
identification, the cutting box labeling and the bag
labeling of RC samples in the field area and selection
of field duplicates were carried out.
The RC drilling cuttings samples were transported to
the facilities of ALS Chemex, an international certified
Laboratory in Antofagasta. The cutting boxes and
pulps of all samples are stored for logging and
reference in the temporal warehouse of the company
at Maria Elena town, II Region, Chile.
Photography of cutting box were performed at the
Maria elena Company facilities.
The RC drilling method was down-the-hole hammer
drilling and the most frequently used hammer bit was
5¾” diameter, although occasionally 5½” bits were
also used. Shallow hole were drilled ranging from 20
to 66m depth. The objective of this drilling campaign
was to investigate and intersect targets zone below
the caliche cover, defined by surface geological
mapping, surface rock chip anomalies and XRF
surface anomalies zones in conjunction with structural
potentially mineralized corridor and chargeability and
resistivity VIP survey results.
The RC drilling was carried out in a 500x500m
spacing regular grid. Local 250x250m RC were
drilled.
Standard splitting and sampling protocols were
implemented.. RC cuttings are reduced by riffle
splitting in the field to 25% of the original drilled
interval. Sample protocols included sample duplicates
for RC (25% of total) at ~5% of total samples
RC samples weight data capture for recovery has
been systematically implemented at the drilling site.
All RC cuttings are logged on site immediately after
drilling, and geologists carried out a Quick Logging
1:1000 scale for preliminary geological interpretation.
The Quick Log captures lithology contrast, general
alteration type and relevant ore mineralization. Paper
RC Quick logs are filed on site and data is input into
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ASX ANNOUNCEMENT
Criteria
JORC Code explanation
in nature. Core (or costean, channel, etc)
photography.
The total length and percentage of the
relevant intersections logged.
Commentary
Sub-sampling
techniques
and sample
preparation
Quality of
assay data
and laboratory
tests
AUSTRALIA | CHILE
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.
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 (ie lack of bias) and
precision have been established.
the pdf database.
The entire drill hole cuttings are detailed logged at
1:100 scale. The logging scheme and logging sheet
reflects the local geology in data capture. Standard
logging and coding sheets were created for this work,
a single person imposed consistency on the logging
and coding processes. The holes mapped have
complete data records that include lithology, alteration
associations, degree and texture, mineralization type
and minerals, intensity, relative abundance in
percentage, texture and occurrence type and
interpreted faulting.
The mapping system, is undertaken on paper logging
forms and data capture has been migrated to digital
capture on the Excel database Once all analysis of
RC sample at 2m support is completed mineralization
coding will be locally revised to include the
mineralogy as continual infill drilling progresses.
Samples from the current program are prepared and
analyzed at ALS Chemex Laboratories (ALS) in
Antofagasta, II Region, Chile. The ALS laboratory
holds ISO 9001:2008 and ISO 17025 certification and
is independent of the company and its subsidiaries.
Samples were typically dried, crushed to 70% passing
-2 mm, and pulverized to 85% passing -0.075 mm.
Pulverized samples were assayed for 33 elements by
atomic emission spectroscopy/inductively-coupled
plasma (ICP-AES) using the ALS ME-ICP61 method
which comprises near-total, four acid digestion,
followed by HCl dilution and ICP-AES determination.
Mechanical Sample preparation was undertaken by
ALS Chemex in a sample preparation facility installed
in Antofagasta. Preparation procedures followed the
following mechanical preparation steps: Drying at
105°C; Primary crushing in a “Rhino” jaw crusher to
70% passing <10# Tyler; Homogenization and
reduction by Jones Riffle Splitter Pulverizing to 85%
passing <150# Tyler; Splitting to 2 sample pulp bags
of approx. 500 g each.
One certified standard reference material were
inserted each 20 samples in the sample pulps stream
during the Company drilling campaign at ALS
Chemex facilities in Antofagasta. New bar codes
sequence for pulps stream were generated and
registered in the excel database and printed.
Correlations between cutting samples and new bar
codes were registered at the excel database and
printed. A complete set of original pulps with bar
codes is storage at ALS facilities. One certified
GEOSTATS standard were used for Copper
reference. Low grade copper standard (code Std Cu
GbM301-4) nominal value: 0,165% CuT. Blanc
material consist of quartz was inserted each 40
meters at ALS facilities for approximately the 2,5% of
the sampled material in the drilling campaign. ALS
customarily inserts pulp duplicates, blanks and
reference materials in the assay batches.
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ASX ANNOUNCEMENT
Criteria
Verification of
sampling and
assaying
JORC Code explanation
Location of
data points
Data spacing
and
distribution
Orientation of
data in
relation to
geological
structure
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.
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.
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.
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
mineralized structures is considered to have
introduced a sampling bias, this should be
assessed and reported if material.
Commentary
The laboratory is clean and well run, with a full-time
chemist supervising operations. Based on a shift
seven days per week.
Assay data are supplied electronically by ALS, and
uploaded into the spread sheet. Additionally ALS
provides an access controlled server data base were
the results could be revised and/or downloaded.
The local coordinate system employed for collar
location is PSAD56 19S in UTM projections. The
collar locations of all holes are surveyed using
standard GPS method..
Drill hole collars were at 250 to 500 metre intervals.
No attempt should be made to establish geological
continuity at this early stage of exploration.
2 metre sample intervals were used.
Sample
security
AUSTRALIA | CHILE
The measures taken to ensure sample
security.
Distrital scale structures are a key factor in the
localization of potential and observed mineralization in
the project area. Faults are highly significant aspects
of the project geology.
The property is located along the Buey Muerto Fault
Zone a north-northwest trending fault splay which
control the location of Antucoya Porphyry deposit, as
a part of a 3 to 15km wide zone of inter-related faults
of the major regional, north-south trending, sinistral
strike-slip Atacama Fault Zone, which was active
during the Early Cretaceous, that extends for much of
the length of the Coastal Cordillera. The Buey Muerto
Fault Zone exhibit a 40 km length trace and contribute
to lithological contact between the Upper Jurassic
plutonic batholith to the west with the upper JurassicCretacic volcanic sequences to the east. The synmineralization structures are likely to have controlled,
the localization of intense fracturing and emplacement
of hydrothermal alteration. The interpreted local
structures in Antucoya west are significant in control
of the limonite-altered outcrops emplacement and in
hosting oxide copper mineralization occurrences
showing a degree of continuity in the north north
west-south south east direction.
The RC drilling campaign included 38 systematically
vertical holes from 20 to 66m depth and 2 holes
inclined to the west (-70°) with an azimuth of 230°.
Samples were transported by ALS using transport
services trucks
and personnel, and were securely locked at the ALS
Labs. Chain-of-custody procedures consisted of filling
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ASX ANNOUNCEMENT
Criteria
JORC Code explanation
Commentary
Audits or
reviews
The results of any audits or reviews of
sampling techniques and data.
out sample submittal forms that accompanied the
sample shipments to confirm that all samples were
received by the laboratory. Sample security consisted
of locking samples, once collected, in the field camp
compound prior to delivery to ALS. This level of
security is considered industry standard for earlystage exploration programs.
Sample rejects and Pulps are currently stored at ALS
in a secure environment. Company sampling data are
stored in an Excel spread sheet.
Assay results were found to remain well beneath 5%
deviation from reported lab results when compared
with duplicate samples.
Section 2 Reporting of Exploration Results
(Criteria listed in the preceding section also apply to this section.)
Criteria
JORC Code explanation
Commentary
Mineral
tenement and
land tenure
status
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 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 Altair project under Option Agreement with SQM
and is comprised of 444 tenements known as
‘Pertenencia’s’ which are registered with and
maintained by SQM and with no encumbrances.
Estrella holds 100% ‘metals’ rights with SQM
maintaining 49% ‘clawback’ upon completion of a
prefeasibility study. Royalty commitments have been
previously published in ASX announcements.
There are no native title interests, historical sites,
national parks, wilderness or environmental settings
to Estrella’s knowledge.
Exploration
done by other
parties
Acknowledgment and appraisal of exploration
by other parties.
Antucoya West has not previously been explored by
any other parties.
Geology
Deposit type, geological setting and style of
mineralisation.
AUSTRALIA | CHILE
Mineralization of the project and other deposits in the
region are part of the Cretacic Porphyry Copper type
deposits, where the most important in the region is
the Antucoya Porphyry Deposit.
The Antucoya porphyry copper deposit is located
approximately 2 km East of Antucoya West Project
and is related to a succession of granodioritic and
tonalitic porphyritic stocks and dykes that were
emplaced within andesitic rocks of the Jurassic La
Negra Formation. Copper-bearing ore occurs as
disseminations in altered rocks and stockwork, and is
hosted by granodioritic and tonalitic porphyries, and
by magmatic to hydrothermal breccias, all within an
area of 1600 x 1200 m. The Antucoya porphyry
copper system is indicated to have been formed
following the change in the stress field along the
magmatic arc from extensional in the Late Jurassic to
transpressive in the Early Cretaceous. The deposit is
located immediately west of the Atacama Fault Zone.
The granodiorite and tonalite porphyries have mutual
intrusion relationships, suggesting they are either
composite intrusions or that they were intruded almost
simultaneously. Four hypogene hydrothermal
alteration assemblages have been recognised at
Antucoya, namely: potassic, mainly within the tonalitic
porphyry, characterized by a biotite, K-feldspar and
quartz assemblage; chlorite-sericite; quartz-sericite;
and propylitic, restricted to the volcanic host rocks of
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ASX ANNOUNCEMENT
Criteria
JORC Code explanation
Commentary
Drill hole
Information
Data
aggregation
methods
AUSTRALIA | CHILE
A summary of all information material to the
understanding of the exploration results
including a tabulation of the following
information for all Material drill holes:
o easting and northing of the drill hole collar
o elevation or RL (Reduced Level –
elevation above sea level in meters) 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.
In reporting Exploration Results, weighting
averaging techniques, maximum and/or
minimum grade truncations (eg cutting of high
grades) and cut-off grades are usually
Material and should be stated.
Where aggregate intercepts incorporate short
lengths of high grade results and lo
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