Castle Minerals Uncovers Hidden Gold Hits Across 4.5km Trend at Nielle
Key Takeaways
- Five previously unreported gold intercepts — including 8m @ 3.65g/t Au from surface — have been identified for the first time through Castle Minerals' review of the Nielle historical database.
- Only ~1km of a 4.5km mineralised trend has been RC-drilled to date, with mineralisation remaining open at depth and along strike across the tested zone.
- Castle inherited a US$3 million+ exploration dataset from prior operators Kodal Minerals and Resolute Mining, covering 40 RC holes, 362 air core holes, and 716 auger holes across the 212km² permit area.
- Six ranked gold targets have been defined across the permit, with an independent JORC-compliant Exploration Target now underway at Target 1, led by a specialist who has contributed to over 3.5Moz of gold resource definition across five West African discoveries.
- Drill contractors are already being engaged in Côte d'Ivoire ahead of permit grant, with a 2,500–3,000m RC and diamond programme planned at Target 1 and a maiden air core programme designed for Target 2.
Multiple drill-ready gold targets defined at Nielle as hidden intercepts emerge from US$3M dataset
Castle Minerals (ASX: CDT) has completed a comprehensive review of the historical exploration database at its Nielle Gold Project in Côte d’Ivoire, unlocking significant new targeting information from more than five years of prior work. The review has defined and ranked six gold targets across the ~212km² permit area, with only ~1km of a 4.5km mineralised trend tested by RC drilling to date.
The scale of untested ground is the key takeaway. Numerous zones along the broader trend remain completely undrilled, and mineralisation within the RC-drilled zone remains open at depth and along strike. Castle is preparing to move quickly once the permit is formally granted, with drill contractors already being engaged in Côte d’Ivoire.
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Previously unreported intercepts strengthen the mineralised case
The most striking finding from the database review is a series of gold intercepts that had never been reported publicly. The standout result from air core drilling is 8m @ 3.65g/t Au from surface (including 3m @ 9.29g/t Au) from hole NLAC028, identified for the first time through this review.
Newly identified RC intercepts not previously announced include:
- 2m @ 2.75g/t Au from 14m [NLRC009]
- 8m @ 1.52g/t Au from 58m [NLRC011]
- 4m @ 1.50g/t Au from 60m [NLRC015]
- 4m @ 2.22g/t Au from 62m [NLRC024]
These results sit alongside previously announced high-grade intercepts that demonstrate the grade quality of the system, including 5m @ 15.42g/t Au from 7m, 13m @ 5.07g/t Au from 12m, and 26m @ 1.95g/t Au from 32m. The full list of previously reported intercepts is detailed in Castle’s ASX announcement dated 19 May 2026. Importantly, mineralisation within the RC-drilled zone remains open at depth and along strike.
Steve Zaninovich, Managing Director
“The historical dataset at Nielle has given us a substantial head start. Previous owners spent more than US$3 million on the project, and historical RC drilling has demonstrated strong gold mineralisation along approximately 1km of the 4.5km mineralised trend, including results of 5m at 15.42g/t Au from 7m, 13m at 5.07g/t Au from 12m and 26m at 1.95g/t Au from 32m. Importantly, this mineralisation remains open at depth and along strike, while significant sections of the broader mineralised trend remain untested.”
What the dataset review covered
The review incorporated five years of historical data generated between 2016 and 2021, representing an estimated US$3 million+ in prior expenditure by previous operators (Kodal Minerals and its joint venture partner Resolute Mining). Castle inherited this dataset on acquisition, providing a significant cost advantage in progressing to drill-ready status.
The integrated dataset covered:
- 40 RC holes (4,498m)
- 362 air core holes (12,096m)
- 716 auger holes
- Satellite remote sensing (ASTER multispectral data)
- Regional airborne magnetics and surface geochemistry
Each dataset was validated, standardised, and interpreted both independently and in combination within a geographic information system (GIS) environment. Targets were then ranked according to the coincidence of favourable structural settings, alteration responses, geochemical anomalism, and drill data.
Understanding orogenic gold and why Nielle’s setting matters
Nielle is interpreted to host an orogenic gold system. This style of deposit is structurally controlled, meaning gold mineralisation is concentrated along shear zones and structural corridors rather than distributed evenly through the rock. Key characteristics include quartz-carbonate veining, sulphide development (principally pyrite), and zones of hydrothermal alteration. These are the features consistently logged at Nielle.
The regional context makes the address compelling. Nielle sits within the Birimian Senoufo greenstone belt in northern Côte d’Ivoire, the same geological province that hosts some of West Africa’s most significant gold deposits.
| Mine Name | Resource Size | Location | Proximity to Nielle |
|---|---|---|---|
| Tongon | 5.0Moz | Côte d’Ivoire | ~50km south |
| Sissingué | 1.5Moz | Côte d’Ivoire | Regional |
| Wahgnion | 3.2Moz | Burkina Faso | Regional |
| Syama | 11.5Moz | Mali | Regional |
The Tongon Gold Mine, located approximately 50km south of Nielle, was previously owned and operated by Barrick and acquired by the Atlantic Group in 2025 for US$305 million. That transaction underscores the strategic value attributed to established gold assets in this district.
It is important to note what an Exploration Target means under the JORC Code (2012). It is a statement of exploration potential quoted as a range of tonnes and grade, applicable where insufficient work has been done to define a Mineral Resource. No Mineral Resource currently exists at Nielle; the Exploration Target being prepared by Castle will provide a framework for assessing the scale of the mineralised system, not a resource estimate.
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Six targets ranked — Target 2 emerges as maiden greenfields priority
The review has defined a hierarchy of six targets across the permit, providing a clear roadmap for Castle’s exploration programme once the permit is granted.
- Target 1: The primary zone, covering the ~1km of RC-drilled mineralised trend. An independent Exploration Target is now underway over this zone.
- Target 2: The first greenfields priority. Positive auger geochemistry has been recorded here, yet no drilling has taken place. Castle is designing a maiden air core programme to test it.
- Target 3: Aligns to the main 4.5km mineralised trend and is ranked as a higher-priority target alongside Target 1.
- Targets 4, 5 and 6: Lower-priority areas with limited to no auger sampling data. These will be addressed through a reconnaissance programme, including tighter-grid airborne magnetic surveys and soil sampling.
The Exploration Target at Target 1 is being led by Ann Ledwidge of Ledex Pty Ltd, a West African orogenic gold specialist who has worked almost exclusively in this discipline since 2010. She led the teams responsible for five gold discoveries and her technical work has contributed to the definition of over 3.5Moz of gold resources across three of those deposits. Ann Ledwidge is also a member of the executive of the JORC Committee, lending considerable credibility to the process.
Steve Zaninovich, Managing Director
“We have initiated an independent Exploration Target over the main RC-drilled zone at Target 1, which will provide an important framework for assessing the scale and potential of the mineralised system. At the same time, we are progressing the design of Castle’s maiden drilling program, including a maiden AC program at Target 2, and are engaging with drill contractors so we can move quickly following grant of the Nielle permit.”
What comes next — the forward work plan
Castle’s near-term work programme across the permit is structured as follows:
- Complete validation of historical collar, survey, assay, lithology, and QA/QC records
- Prepare a JORC Code (2012)-compliant Exploration Target over the Target 1 mineralised trend
- Following permit grant: implement infill and deeper RC and diamond drilling at Target 1 (planned range of approximately 2,500–3,000m)
- Establish a reconnaissance maiden air core programme at Target 2
- Acquire higher-resolution airborne magnetic surveys and interpret complementary radiometric data to refine structural targets
- Tighten the coarse soil sampling grid over specified target areas
- Undertake field validation of priority targets prior to drilling
The combination of demonstrated high-grade gold mineralisation, a large prospective landholding in a world-class geological address, and a historical dataset representing more than US$3 million in prior expenditure gives Castle a material head start. The company continues to work closely with project vendor Golden Arrow SARL on the conditions precedent associated with grant of the Nielle permit, as outlined in its announcement dated 19 May 2026.
Castle’s Côte d’Ivoire gold exploration expansion extends beyond Nielle, with the company advancing multiple project-level work programmes across its West African portfolio in parallel with the Nielle permit process.
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