Spectral Footprints of Gold: Eco-Friendly Exploration in Wasa Amenfi District of Ghana

Abstract. Gold mining plays a central role in Ghana’s national economy. However, conventional exploration approaches, particularly within artisanal and small‑scale mining sectors, often rely on trial‑and‑error methods that lead to extensive environmental degradation. The absence of systematic geological exploration before mining has contributed to deforestation, soil contamination, and landscape disturbance in many gold-bearing regions. This study introduces an eco-friendly and cost‑effective remote sensing-based approach, referred to as Green Gold Exploration, for identifying potential gold-rich zones before field excavation. Using Sentinel-2 surface reflectance imagery processed on the Google Earth Engine (GEE) platform, iron oxide and clay mineral spectral indices were derived to detect hydrothermal alteration features commonly associated with gold mineralization. The Wasa Amenfi District in the Western Region of Ghana, a historically active gold‑producing area, was selected as the study area. Field validation was conducted using approximately 2,000 soil samples collected at 40 cm depth within a 1 km² sampling grid and analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to determine gold concentrations in the soil. Spatial interpolation of laboratory results was performed using Inverse Distance Weighting (IDW). Results demonstrate spatial correspondence between high index values and elevated gold concentrations, with most confirmed gold occurrences located within 1 km of identified alteration zones. The findings confirm the potential of satellite-based spectral analysis as a sustainable pre-exploration tool capable of reducing environmental impacts, lowering exploration costs, and supporting informed decision-making before mining activities.