Costerfield – True Blue Exploration Update
Costerfield – True Blue Exploration Update
PERTH, Australia, July 05, 2026 -- Alkane Resources Limited (ASX: ALK; TSX: ALK; OTCQX: ALKRY) (‘Alkane’ or ‘the
Company’) is pleased to announce the latest exploration results for extension and infill drilling of the True Blue deposit, located
2 km west of the active underground workings at its Costerfield Operation in central Victoria, Australia.
Program Summary
• An additional 33 holes targeting the Freeman veining within the True Blue deposit have been drilled since Alkane’s
previous update (ASX announcement 15 October 2025 titled ‘Costerfield Resource and Reserve Statement).
• The new drilling predominantly targeted infill of the upper portion of the deposit and has significantly increased
confidence in understanding the vein geometry and grade-controlling structures.
• The higher resolution granted by the infill drilling indicates there is further veining complexity that serves to break-up a
previously interpreted high-grade panel.
• Current and future exploration drilling will target along-strike repetitions of mineralisation at True Blue both to the north
and south, and investigate the link between it and the West Costerfield prospect.
True Blue Assay Highlights
• From Freeman (700) Vein:
◦ 57.6g/t gold and 25.4% antimony over 0.25m (ETW 0.17m) in TB055
◦ 20.9g/t gold and 19.5% antimony over 0.31m (ETW 0.22m) in TB057
◦ 4.3g/t gold and 6.4% antimony over 0.8m (ETW 0.63m) in TB080
◦ 30.1g/t gold and 14.8% antimony over 0.27m (ETW 0.17m) in TB065
• From associated veins
◦ 84.1g/t gold and 15.4% antimony over 0.48m (ETW 0.36m) in TB084 (702 splay)
◦ 17.9g/t gold and 1.7% antimony over 3.2m (ETW 1.4m) in TB053 (705 vein)
◦ 19.3g/t gold and 29.3% antimony over 0.22m (ETW 0.16m) in TB079
◦ 11.2g/t gold and 5.7% antimony over 0.77m (ETW 0.54m) in TB055
Alkane Managing Director & CEO, Nic Earner, said:
“The infill drilling of True Blue gives us the geological confidence needed to proceed with our plans for development of the
deposit. The geological context gained from the drilling has also enhanced the model for further targeting along the True Blue
Corridor. True Blue is certainly more complex than our original estimates, we are encouraged by the progress made and
excited by the targets yet to be tested.”
Costerfield Gold-Antimony Field
Alkane Resources Ltd 100%
The Costerfield gold-antimony deposit was discovered in 1861, antimony having been already identified in the district as early
as 1853 as prospectors attracted to the McIvor (Heathcote) alluvial gold rush began to explore the surrounding hills for the
primary deposits. Several lodes along a 3km corridor were rapidly opened up with the bulk of historical production coming from
leases at the northern end of the field; the Costerfield (Main), Bombay and Minerva mines. Production from these mines
primarily took place in two phases, between 1861-1883 and 1903-1924, and a short-lived attempt at redeveloping the mine
occurred between 1933-1939.
Modern mining has been continuous since 2006, when Australian Gold Development commenced underground operations at
Augusta, at the southern end of the field. AGD’s Costerfield operation was purchased by Mandalay Resources in 2010, and
extraction of the vertically continuous vein system has progressively moved north beneath the Costerfield, Minerva and
Bombay group of mines, where Mandalay’s high-grade Youle and Shepherd lodes were discovered.
The True Blue deposit is first recorded in an 1864 government survey map of the Costerfield area, and was initially worked
down to the water table for a short time after discovery. It has been subject to minor prospecting activity since, and in 2010
Mandalay Resources drilled the first diamond drillhole below the surface workings. However, it was not until 2022 with drillhole
TB010 that economic grades were encountered and testing of the Freeman veining became a major focus of exploration at
Costerfield.
Figure 1. Regional map of the Costerfield Project in GDA2020 grid showing Alkane tenements and the main corridors of
mineralisation identified, highlighting the location of the True Blue deposit.
Deposit Geology
True Blue is located on the western flank of the Costerfield Dome, hosted by Silurian marine siltstones of the Costerfield
Formation which correlate via marker beds to the same stratigraphic level as the Youle, Brunswick and Augusta deposits. The
siltstone is extensively thickened by duplex ramping into a doubly plunging antiformal thrust stack or dome, within which the
bulk of observed mineralisation sits. The main mineralised structures are situated within the western limb of the dome, but
many other parallel vertical shears with varying degrees of mineralisation are found closer to the hinge and on the eastern limb.
The dominant mineralised structure identified at True Blue has been named the Freeman Vein, and is assigned the Costerfield
resource code of 700. Other modelled veins within the deposit include the 702 and 705, which lie close by east and west of the
Freeman vein respectively (Figure 2), and the 710 and 720 which occur parallel further east.
The cap of the target veins is well defined by the Wombat Fault, which is strongly lithologically controlled and runs along a
~50cm thick isolated sandstone bed that appears to have acted as the main detachment plane for the thrust stack. The fault
is observed in the same stratigraphic position over the entire dome. Lower tenor mineralisation, including the surficial True Blue
prospect, occurs above the fault somewhat offset to the east from the Freeman veining.
The footwall boundary of the target system is also well understood. The large, west-dipping Komodo thrust fault truncates the
Freeman veining and the host dome. It is also observed that the fault follows the same distinctive sandstone marker bed in its
footwall. The apparent along-plane displacement along the Wombat-Komodo sandstone detachment is thus significant,
approaching at least 1,000m if restored to its original planar and horizontal position. Mineralisation of moderate tenor has been
observed in drilling below the Komodo Fault in an offset position and remains a target for further testing.
Mineralisation at the north and south boundaries of the current resource is of lower grade, which appears to correlate with the
increasing plunge of the host dome stratigraphy and bedded structures at the extremities. This observation is in line with other
mined Costerfield deposits and reinforces Alkane’s plan to locate and target further dome repetitions along strike in the future.
The current round of infill drilling has resolved the Freeman vein into a sheeted series of vertical north-south veins, generally
single-generation fracture fill quartz-stibnite similar in nature to the Kendal deposit at Costerfield as opposed to shear-hosted
mineralisation such as found at Brunswick/Cuffley. Mineralised linking structures cross between primary veins at oblique
angles. Bedding parallel and subparallel laminated quartz veins and faults also intersect the veins, creating local grade
boundaries and complex splay vein arrays. These factors combine to introduce localised complexity (and upside potential) into
the system which is otherwise remarkably planar at the deposit scale.
Figure 2. Geological cross section of the True Blue gold-antimony vein system at mine northing 7400N, showing the Freeman
vein and associated mineralisation positions relative to the True Blue antiformal dome, and its relationship with known
bounding and crosscutting faults. n.b. All traces of new drillholes intersecting the Freeman Vein are illustrated, some appear
to not intersect due to the off section effect of the lode system striking ~30 degrees east of mine grid north (see plan section).
Drilling Results
Since the previous release (refer to the Costerfield Resources and Reserves Statement FY25 released on the ASX and TSX on
15 October 2025), 33 growth and infill holes have been completed, totalling 19,012m of diamond drill core. The recent drilling
has been concentrated on infilling the upper portion of the Freeman vein and refining structural information to build confidence
in the geological model. The deposit from approximately 800RL down to the Komodo Fault footwall contact remains relatively
sparsely infilled. Several ore-grade intercepts were made on the Freeman vein, the best of which was from drillhole TB055
(Figure 6) which resulted in 57.6g/t gold and 25.4% antimony over 0.25m (ETW 0.17m). The latest hole drilled into the deposit,
TB084, intersected a wide zone of veining (Figure 7) that contained high grade gold and antimony, interpreted to represent a
linking zone between the 702 and 705 veins. The best interval within this zone graded 84.1g/t gold and 15.4% antimony over
0.48m (ETW 0.36m).
Figure 3. True Blue Deposit Plan Section with major True Blue vein best fit traces displayed, recent drill traces and labels for
new intercepts of > 6g/t AuEq when diluted over 1.8m. Older significant drill intercepts are displayed as smaller, unlabelled
icons.
Figure 4. Long Section True Blue deposit with major vein target envelopes displayed, recent drill traces and labels for new
intercepts of > 6g/t AuEq when diluted over 1.8m. Older significant drill intercepts are displayed as smaller, unlabelled icons.
Figure 5. Schematic Cross section looking north at mine northing 7250N showing True Blue veins and > 6g/t AuEq new
intercepts labelled. Older significant drill intercepts are displayed as smaller, unlabelled icons. Intercept eastings have been
adjusted to cluster around their assigned veins at this northing to combat off-section effect over the length of the deposit.
Figure 6. Core tray photo of the Freeman vein intercept described in this announcement, 57.6g/t gold and 25.4% antimony over
0.25m (ETW 0.20m) in drillhole TB055. The intercept is stibnite-rich with only minor quartz while still carrying significant gold,
a common characteristic of the Freeman vein.
Figure 7. Core tray photograph of the Freeman-702 vein splay zone intersected in TB084, where the highest grade interval of
the drill program was intersected.
Future Plans
Going into FY26-27, continued drilling at True Blue will focus on testing along strike to identify additional deposits. Nearby
prospectivity is apparent in several directions from the current resource:
• North – Soil sampling indicates the True Blue geochemical anomaly may persist at least several hundred metres further
north than the current edge of the Freeman resource. At surface approximately 200m north of the resource, outcrops a
shear that hosts an albitised and silicified felsic dyke that is strongly anomalous in antimony with pXRF analysis,
further evidence indicating persistence of the mineralised system northward from the tested area.
• South – Diamond drillhole TB022 in early 2024 intersected a wide zone of gold-antimony mineralisation approximately
550m south of the current resource boundary. This zone included 2.6g/t gold over 2.38m (2.00m ETW) (Refer to 28
January 2025 TSX Announcement - Mandalay Intercepts 578 g/t Gold and 20% Antimony over 0.47 Metres at True
Blue) Geological interpretation of the drill data suggests that this area may host a repetition of the domal structure that
appears to have been important for developing economic mineralisat Freeman and is a high priority for further testing.
• Depth – The footwall of the Freeman vein system is defined by the regional-scale Komodo thrust fault. Tails of several
diamond drillholes at True Blue have encountered vertical mineralised veins below this fault, including veins drilled in
hole TB037 discussed in the previous release (Refer to TSX Announcement - 21 July 2025 - Mandalay Extends High-
Grade True Blue Discovery. The veins in the Sub-Komodo domain have not been explicitly targeted to date and has
high potential for hosting a large mineralised system.
• East – The West Costerfield prospect sits approximately 800m east of the True Blue deposit and shares a potential ore
fluid pathway – the Komodo Fault. At West Costerfield, the fault is much closer to surface, and exhibits localised
intense hydrothermal brecciation. The structural environment below the Komodo Fault has not been drill tested away
from True Blue, and as the depth prospectivity at True Blue demonstrates is likely to host mineralised veins that are
offset from the surface deposit at West Costerfield.
The exploration targets described herein are conceptual in nature. There has been insufficient exploration to define a mineral
resource in these areas and it is uncertain if further exploration will result in the delineation of a mineral resource.
An updated True Blue resource will be announced as part of Alkane’s upcoming Resource and Reserves Statement.
This document has been authorised for release to the market by Nic Earner, Managing Director and CEO.
ABOUT ALKANE ‐ www.alkres.com ‐ ASX:ALK | TSX: ALK | OTCQX: ALKRY
Alkane (ASX:ALK; TSX:ALK; OTCQX:ALKRY) is an Australia-based gold and antimony producer with a portfolio of three
operating mines across Australia and Sweden. The Company has a strong balance sheet and is positioned for further growth.
Alkane’s wholly owned producing assets are the Tomingley open pit and underground gold mine southwest of Dubbo in
Central West New South Wales, the Costerfield gold and antimony underground mining operation northeast of Heathcote in
Central Victoria, and the Björkdal underground gold mine northwest of Skellefteå in Sweden (approximately 750 km north of
Stockholm). Ongoing near-mine regional exploration continues to grow resources at all three operations.
Alkane also owns the very large gold-copper porphyry Boda-Kaiser Project in Central West New South Wales and has
outlined an economic development pathway in a Scoping Study. The Company has ongoing exploration within the surrounding
Northern Molong Porphyry Project and is confident of further enhancing eastern Australia’s reputation as a significant gold,
copper and antimony production region.
Competent / Qualified Persons Statement
Certain information in this announcement relating to Exploration Results has been previously released to the ASX. Alkane
confirms that it is not aware of any new information or data that materially affects the information included in those market
announcements and that all material assumptions and technical parameters underpinning the estimates and Exploration
Results in those announcements continue to apply and have not materially changed.
The information in this report that relates to the Costerfield Exploration Results is based on, and fairly represents, information
compiled and verified by Mr Chris Davis. Mr Davis is a Chartered Professional (Geology) of the Australasian Institute of Mining
and Metallurgy (MAusIMM CP(Geo)) and a Member of the Australian Institute of Geoscientists (MAIG).
Mr Davis has sufficient experience that is relevant to the style of mineralisation and type of deposit under consideration and to
the activity being undertaken to qualify as a Competent Person as defined in the 2012 Edition of the “Australian Code for
Reporting of Exploration Results, Mineral Resources, and Ore Reserves” (JORC Code).
For the purposes of National Instrument 43-101 – Standards of Disclosure for Mineral Projects (‘NI 43-101’), the scientific and
technical information contained in this announcement relating to the Costerfield Exploration Results has been prepared under
the supervision of, and approved by, Mr Chris Davis, who is a “qualified person” as defined in NI 43-101. Mr Davis is employed
by Alkane as Chief Geologist and, as an employee of Alkane, is not considered independent of Alkane within the meaning of
NI 43-101.
Mr Davis consents to the inclusion in this report of the matters based on his information in the form and context in which they
appear.
Cautionary Note Regarding Forward-Looking Information and Statements
This announcement contains certain forward-looking information and forward-looking statements within the meaning of
applicable securities legislation and may include future-oriented financial information or financial outlook information
(collectively Forward-Looking Information). Actual results and outcomes may vary materially from the amounts set out in any
Forward-Looking Information. As well, Forward-Looking Information may relate to: future outlook and anticipated events;
expectations regarding exploration potential; production capabilities and future financial or operating performance, including
AISC, investment returns, margins and share price performance; production and cost guidance and the timing thereof; issuing
updated resources and reserves estimate and the timing thereof; the potential of Alkane to meet industry targets, public profile
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"expect", "upside", "growth" and similar expressions and phrases or statements that certain actions, events or results "may",
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Although Alkane believes that the expectations reflected in the Forward-Looking Information are reasonable, undue reliance
should not be placed on Forward-Looking Information since no assurance can be provided that such expectations will prove to
be correct. Forward-Looking Information is based on information available at the time those statements are made and/or good
faith belief of the officers and directors of Alkane as of that time with respect to future events and are subject to risks and
uncertainties that could cause actual results to differ materially from those expressed in or suggested by the Forward-Looking
Information. Forward-Looking Information involves numerous risks and uncertainties. Such factors include, without limitation:
risks relating to changes in the gold and antimony price.
Forward-Looking Information is designed to help readers understand Alkane’s views as of that time with respect to future
events and speak only as of the date they are made. Except as required by applicable law, Alkane assumes no obligation to
update or to publicly announce the results of any change to any forward-looking statement contained or incorporated by
reference herein to reflect actual results, future events or developments, changes in assumptions or changes in other factors
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be drawn that the company will make additional updates with respect to those or other Forward-looking Information. All
Forward-Looking Information contained in this announcement is expressly qualified in its entirety by this cautionary statement.
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implied, is made as to the fairness, accuracy, completeness or correctness of the information, opinions or conclusions
contained in this announcement. To the maximum extent permitted by law, none of Alkane, its directors, officers, employees,
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from fault or negligence on the part of any of them or any other person, for any loss arising from the use of this announcement
or its contents or otherwise arising in connection with it.
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purchase or sale of any security, and neither this announcement nor anything in it shall form the basis of any contract or
commitment whatsoever.
APPENDIX 1 – Tabulated Drilling Results
Significant intercepts from the True Blue infill drilling program at Costerfield
Drill Hole ID From (m) To (m) Interval (m)
Estimated
True Width
(m)
Au (g/t) Sb (%)
Gold-equiv.
grade diluted
to 1.8 m (g/t)
Interpreted
Vein
TB051 528.32 528.44 0.12 0.09 0.1 0.6 0.1 700
TB052 539.77 540.01 0.24 0.15 45.2 21.1 8.2 700
TB054 510.28 510.43 0.15 0.11 1.0 0.1 0.1 700
TB055 523.83 524.08 0.25 0.17 57.6 25.4 11.5 700
TB056 509.30 509.84 0.54 0.40 2.3 3.5 2.4 700
TB057 505.95 506.26 0.31 0.22 20.9 19.5 8.2 700
TB058 514.95 515.44 0.49 0.33 13.9 0.7 2.9 700
TB060 524.90 525.11 0.21 0.16 0.8 0.0 0.1 700
TB061 560.35 561.25 0.90 0.62 2.4 1.4 1.9 700
TB063 510.26 514.75 4.49 3.48 0.0 0.0 0.0 700
TB064 641.36 641.65 0.29 0.17 19.6 1.3 2.2 700
TB065 638.94 639.21 0.27 0.17 30.1 14.8 6.0 700
TB066 667.79 667.97 0.18 0.10 5.7 1.5 0.5 700
TB067 603.21 606.00 2.79 1.77 1.5 0.3 2.3 700
TB069 736.86 737.00 0.14 0.01 0.1 6.3 0.4 700
TB072 454.86 455.21 0.35 0.20 37.3 3.5 5.2 700
TB073 555.45 555.55 0.10 0.07 32.4 21.2 3.4 700
TB075 547.21 547.38 0.17 0.13 2.3 8.6 1.7 700
TB075W2 543.70 543.85 0.15 0.12 7.7 15.4 2.9 700
TB076 520.19 520.54 0.35 0.25 5.7 4.3 2.2 700
TB077 496.86 496.99 0.13 0.10 1.5 7.4 1.0 700