New Blog: Strengthening Resource Modelling Practices in Ghana’s Greenstone Belts

At a recent conference, Snowden Optiro Principal Consultant Senzeni Mandava shared her expertise on how to strengthen Mineral Resource modelling for Ghana’s shear-hosted gold deposits. Her presentation focused on how combining geological understanding with data-driven techniques can significantly improve confidence in Mineral Resource Estimates (MREs).

---

Understanding Ghana’s Greenstone Belts

Senzeni began by setting the geological context of Ghana’s prolific Birimian greenstone belts, which host world-class gold deposits such as Obuasi, Tarkwa, Wassa, Bibiani, and Ahafo. These deposits are typically associated with shear zones and hydrothermal alteration, requiring careful interpretation of structural controls.

She emphasised that integrating geological and structural mapping into resource modelling is essential. Aligning block models with dominant shear orientations and incorporating structural trends into anisotropy models can greatly improve estimation accuracy.

---

Strengthening Exploration and Data Quality

A recurring theme throughout Senzeni’s session was the critical role of data quality and geological discipline in exploration. Common mistakes – such as inconsistent logging, poor sample recovery, and inadequate QA/QC – can undermine the reliability of models.

Her advice was clear:

“Reliable models start with reliable data. Rigorous QA/QC – duplicate sampling, standards, blanks, and validation dashboards – should never be treated as an afterthought.”

Senzeni encouraged maintaining meticulous drilling records, validating assay data, and using Datamine’s integrated database validation tools for real-time QA/QC monitoring to quickly detect and correct data anomalies.

---

Managing Coarse Gold and the Nugget Effect

One of the biggest challenges in West African gold systems is managing coarse gold and the nugget effect. Senzeni highlighted the importance of understanding grade variability and adopting appropriate sampling protocols.

She recommended techniques such as:

• Screen fire assays
• Decile-based top cuts
• Simulation-based estimation methods like Sequential Gaussian Simulation (SGS)

She also noted that twin-hole analysis remains essential for quantifying short-range variability and minimising bias.

---

Geological Domaining and Structural Modelling

According to Senzeni, geological domaining forms the backbone of defensible resource models. Domains should be defined by lithology, alteration intensity, and structural continuity, not just grade thresholds.

Thoughtful domain design, supported by statistical and variography analysis, ensures that mineralisation continuity is properly captured. She encouraged collaboration between geologists and resource modellers and the use of visualisation tools to refine domains effectively.

---

Variography, Estimation, and Model Validation

Senzeni shared practical workflows for variography and estimation, including the use of directional variogram maps to identify anisotropy, and Kriging Neighbourhood Analysis (KNA) to optimise block size, search radius, and sample count.

She also outlined Snowden Optiro’s recommended multi-pass estimation strategy – from variogram range to extended search distances – and highlighted the importance of cross-validation using swath plots, QQ plots, and bias checks to confirm model accuracy.

“A robust resource model isn’t defined by complexity; it’s defined by how transparently it can be validated.”

---

Driving Technical Confidence Across West Africa

Senzeni concluded by reinforcing that technical excellence begins with geological understanding, data discipline, and collaboration. Embedding a strong QA/QC culture, leveraging advanced fit-for-purpose geological and mining software, and encouraging teamwork between exploration geologists, resource modellers, and mine planners can lead to more predictable outcomes and confident decision-making from exploration through to production.

If you would like to contact Senzeni: contact@snowdenoptiro.com

---

About Snowden Optiro

Snowden Optiro provides independent mining advisory, consulting, and professional training to mining and exploration companies, financial institutions, and investors worldwide. With offices across major mining regions, Snowden Optiro supports clients in resource estimation, mine geology, QA/QC, and reconciliation, underpinned by a strong commitment to technical excellence and professional integrity.

👉 Learn more about our services and training at www.snowdenoptiro.com.

SNOWDEN OPTIRO is a resources consulting and advisory group that provides independent advice, consulting and training to mining and exploration companies, their advisors and investors.

We help mine developers to advance their projects, mining companies to improve their operations and their professionals, and investors to de-risk their investments by the provision of quality advice, training and software in the field of Mineral Resources and Mineral/Ore Reserves.

LINK to Snowden Optiro website