Manna Hill Project Exploration Update
Cobra extends Manna Hill drilling programme to five additional holes based on visual observations of primary copper and molybdenum mineralisation.
- Drillholes completed to date 13
- Total metres drilled to date 2,300m
- Drillholes showing visual copper/molybdenum signs 7 of 13
- Strike length of Blue Rose mineralisation 1.6km
- Further drillholes planned up to 5
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Cobra (LSE: COBR), a South Australian mineral exploration and development company, is pleased to announce that, based on visual observations of drill cuttings, it has decided to immediately extend its Stage 1 Reverse Circulation ("RC") drill programme at the Manna Hill Copper Project by up to a further five drillholes.
Highlights:
13 drillholes completed to date, totalling 2,300m where:
o Visible sulphides and alteration support broad zones of primary mineralisation beneath and along strike of defined oxide mineralisation.
o Visible primary copper and molybdenum mineralisation occurs proximal to porphyry type quartz monzonite and diorite intrusions, that have been intersected in multiple drillholes and mapped at scale beyond defined mineralisation at Blue Rose.
o Seven of 13 drillholes completed to date display visual signs of copper oxide and sulphides or molybdenite
o Broad alteration zones support the thesis for a large-scale porphyry system.
- The programme will be increased by up to a further five drillholes based on observations for primary mineralisation and to gain further geological and geochemical detail of the greater porphyry system.
- Drilling is expected to be completed by next week, with first assays anticipated in March.
Cobra has a 12-month option to acquire the Manna Hill Project and will focus initially on the Blue Rose priority prospect ("Blue Rose") where existing drilling has intersected copper-gold mineralisation across 1.6km of strike immediately adjacent to a geophysical anomaly interpretated as a porphyry intrusion1.
To watch a video of Rupert Verco, Managing Director discussing drilling follow the link: https://investors.cobraplc.com/link/e9QMDe
Cautionary Statement: Visual estimates of mineral abundance should never be considered a proxy or substitute for laboratory analyses where concentrations or grades are the factor of principal economic interest. Visual estimates also potentially provide no information regarding impurities or deleterious physical properties relevant to valuations. A summary log of visual estimates of mineralisation for drill holes MHRC0001 - MHRC0013 is provided in Table 1 below.
Rupert Verco, Managing Director of Cobra, commented:
"Whilst visual observations are not results, the geological observations being made from this drilling programme to date are encouraging for a scalable copper discovery.
The team, along with Bullion drilling, has done an exceptional job battling challenging conditions and we are grateful for the perseverance and professionalism that they have shown to overcome extreme temperatures."
The Blue Rose Prospect is of skarn-replacement type where previous exploration has defined copper-gold-molybdenum across 1.6 km of continuous strike where drilling has defined the previous intersections:
o [RABR822] 47m at 2.2% Cu and 0.76 g.t Au from 11m
o [RCBR025] 132m at 0.52% Cu from 8m including 48m at 1.04% Cu
o [RABR152] 41m at 1.6% Cu from 9m including 18m at 2.03% Cu
o [RABR205] 43m at 0.6% Cu from 12m
o [RCBR030] 52m at 0.77% Cu and 0.94 g/t Au from 80m
o [RABR198] 24m at 1.0% Cu from 18m incl. 3m @ 1.23g/t Au
o [RCBR021] 23m at 1.4% Cu from 73m incl. 12m @ 0.71g/t Au
Geophysics including gravity, induced polarisation and magnetics have been used in collaboration with geochemistry to refine the interpretation of both the stratigraphic unit hosting shallow skarn mineralisation, and porphyry mineralisation that is interpreted to envelop a remnant magnetised intrusion. Whilst past exploration has intersected quartz monzonite intrusions proximal to skarn mineralisation, their relationship and influence on mineralisation is not clearly understood. This RC programme has generated the first pXRF multi-element dataset that has enabled Cobra and its consultants to assess the geochemistry of the system and evaluate the data in the context of a porphyry setting.
Observations from completed drilling support depth continuities of shallow mineralisation whilst also defining key indicators for mineralisation control and system continuity. As a result, up to five additional holes will be drilled to further test for scale and for potassic porphyry mineralisation.
Figure 1: Progress plan of completed and further drill collars
Figures 2 & 3: Sections 428625mE and 429025mE that highlight downhole visual observations of oxide and sulphide mineralisation below previous drilling and intersected intrusions relative to mineralisation within drillhole MHRC0003.
Key points:
- Several holes contain chemistry that indicates that alteration and mineralisation are proximal to, or within a potassic zone (Figure 4).
- Potassic (biotite and K-feldspar) alteration occurs proximal to intersected intrusions. This alteration is associated with copper sulphides and molybdenite.
- Intrusions (quartz monzonite, diorite and dacites) have been identified at surface, well beyond the strike of Blue Rose mineralisation where copper mineralisation is apparent at surface along with strong nontronite (after sulphide) alteration (Figures 5 and 6).
- Dyke swarms are important within porphyry systems and understanding the geochronology sequence and their enrichment potential is an important process for identifying the structures that host the highest-grade mineralisation.
- At the completion of drilling, geochemistry will enable alteration modelling and porphyry vectoring.
Figure 4. pXRF data from MHRC0013 downhole sample composites that highlight potassic chemistry associated with mineralisation from 130-140m.1
Figures 5 & 6: Cobra geologist, Isaac Pepe inspecting nontronite alteration adjacent to an outcropping intrusive diorite located 2km southeast of the Blue Rose Prospect and a hand specimen containing secondary copper oxides (chrysocolla).
Table 1: Visual estimation of copper and molybdenum mineralisation
| Hole ID | From | To | Copper Oxide % (Malachite, chrysocolla and Jarosite) | Chalcopyrite % | Molybdenite % |
|---|---|---|---|---|---|
| MHRC0003 | 24 | 26 | 1-2 | ||
| 32 | 52 | 2-3 | |||
| 58 | 60 | 1-2 | |||
| 62 | 64 | 1-2 | |||
| 68 | 72 | 2-3 | |||
| 78 | 80 | 1-2 | |||
| 86 | 90 | 1-2 | |||
| 106 | 108 | 0.5-1 | trace | ||
| 124 | 126 | 0.5-1 | trace | ||
| 144 | 150 | 1-1 | trace -0.5 | ||
| 152 | 154 | 1-2 | trace-0.5 | ||
| MHRC0001 | 12 | 42 | 0.5-1 | ||
| 54 | 62 | 0.5 | 0.5-1 | ||
| 96 | 100 | 0.5-1 | |||
| 112 | 118 | 1-2 | |||
| 126 | 130 | 1-2 | |||
| MHRC0008 | 124 | 130 | 1-2 | ||
| MHRC0009 | 26 | 62 | 1-2 | ||
| incl. | 32 | 38 | 2-3 | ||
| 118 | 132 | 1-2 | 1-2 | ||
| MHRC0010 | 20 | 30 | 2-3 | ||
| 94 | 98 | 1-2 | |||
| MHRC0011 | 20 | 30 | 2-4 | ||
| 30 | 44 | 1-2 | |||
| MHRC0013 | 64 | 100 | 1-2 | ||
| incl. | 74 | 84 | 2-3 | ||
| MHRC0013 | 102 | 104 | 1-2 | ||
| 106 | 114 | 1-2 | |||
| 118 | 144 | 1-2 |
References
- Dr Ross R Large, 2025 "Simple graphical tools to understand the relationship between porphyry composition, hydrothermal alteration, mineralogy and copper-gold grades in porphyry copper deposits", Ore Geology Reviews. 182:106581
About the Manna Hill Project
The Manna Hill Project (the "Project") represents South Australia's premier porphyry prospect in the state that holds around 70% of Australia's copper reserves. The project is comprised of multiple early stage porphyry and skarn prospects.
The Project sits along the national railway and Barrier Highway between the mining hub of Broken Hill, the port and base metals smelter and Port Pirie and the City of Adelaide.
- Cobra RNS: Option to Acquire Significant Copper Project, 26 August 2025
References:
- Cobra RNS: Option to Acquire Significant Copper Project, 26 August 2025
Regional map showing Cobra's tenements in South Australia
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Appendix 1: JORC Code, 2012 Edition - Table 3
| Criteria | JORC Code explanation | Commentary |
| Logging | · 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. | · Historic logging has been completed with a number of different geological logging codes. These are being translated into a standardized logging format prior to entry into the Cobra Drillhole Database · All holes were qualitatively geologically logged for their entire length by suitably qualified Discover Co geologists and recorded onsite into Discover Co's MX Deposit database. · Mineral Resources have not been estimated; however, the quality of the logging is expected to be suitable for low-confidence resource estimation purposes. · The detail of geological logging is considered sufficient for exploration and resource definition drilling. · Logging included visual estimates for copper oxides and sulphides aswell as pyrite content · All intersections were logged. |
| Sub-sampling techniques and sample preparation | · 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. | Historic · Historic sampling has not been assessed. Current · For each metre, a Metzke cone split sample was collected in a calico bag. A portable XRF unit was used to screen a selected interval of 1m RC bulk samples for anomalous copper values. Where copper value readings exceeded ~200 ppm Cu, sampling was conducted at 1m intervals using the Metzke cone split samples. · Weights of samples submitted for assay averaged 2.5 kg and ranged between 1.8 to 4.1 kg. Sample size is considered appropriate for the material sampled. · Commercially certified reference material of known copper grades and of suitable matrix were included in the laboratory assay sequence at a rate of 1 per 50 samples. · First-split duplicate samples were collected at a rate of 1 per 50 samples. · A coarse blank sample was inserted 1 in every 50 samples. · The Competent Person considers that the sample size is appropriate to the grain size of the material being sampled. |
| Location of data points | · Accuracy and quality of surveys used to locate drill holes (collar and down-hole surveys), trenches, mine workings and other locations used in Mineral Resource estimation. · Specification of the grid system used. · Quality and adequacy of topographic control. | Historic · Historic Drillholes were recorded with a number of different datums. · Validation of the datums used for each program have been conducted and are continuing. · The key historic drilling used for planning of the January 2026 drill program have high confidence in the datum used and have been assessed in the field Current · Drill hole locations were determined by handheld GPS with a nominal accuracy of +/- 5 metres. · All coordinates and maps presented here are in the MGA Zone 53 GDA94 coordinate system. · Topographic control is provided by Aerometrex Reigel VQ-780ii Airborne Laser Scanner producing LiDAR digital elevation data at 0.1m accuracy with collar heights extracted from a DTM produced from the LiDAR data. |
| Audits or reviews | · The results of any audits or reviews of sampling techniques and data. | · |
| Appendix 2: Section 2 reporting of exploration results | ||
| Criteria | JORC Code explanation | Commentary |
| Mineral tenement and land tenure status | · Type, reference name/number, location and ownership including agreements or 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. | · Blue Rose is located on EL6009 that is held by Hamelin Gully Pty Ltd. Manna Hill Mining Pty Ltd, a subsidiary of Cobra Resources Plc has a 12-month option to acquire Hamelin Gully. · This drilling forms part of the company's strategy to seek shareholder approval to exercise the option. · A 1% Over Riding Royalty Agreement is registered between Hamelin Gully and Springton Trust A Native Title Agreement is in place between the Wilyakali People and Hamelin Gully Pty Ltd Cultural heritage surveys have been completed over EL6009, clearing proposed drill sites |
| Further work | · The nature and scale of planned further work (eg 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. | · RC drill program at Blue Rose, Desert Rose and Double Delight in early January 2026 · Follow up diamond drilling at Desert Rose · Greenfields soil sampling program |
Cleaned text: letterheads, contacts and legal notices removed. View the original announcement ↗ · Company filings. Not investment advice.