Characterisation of Industrial Salt from Mined Sources in Borno State, North East Nigeria

Rock salt deposits mined from inland salt lakes and alluvial flats in the Lake Chad basin serve as an important traditional mineral resource for communities in Borno State, yet comprehensive chemical characterisation distinguishing food-grade quality from industrial purity has not been widely conducted. This study characterises rock salt samples collected from three artisanal mining sites in Borno State, North East Nigeria, for their chemical composition. Sodium chloride content is determined by the Mohr argentometric titration method. Moisture content, sulphate, calcium, magnesium, iron, potassium, and heavy metal concentrations including lead, cadmium, and arsenic are measured using standard wet chemistry and atomic absorption spectrophotometric methods. Water-soluble and acid-soluble impurity fractions are characterised separately to distinguish inherent geological impurities from surface contamination. Results are compared against Nigerian Industrial Standard specifications for refined edible salt and international standards for industrial rock salt. The study also assesses colour, grain size distribution, and crystallographic regularity through optical microscopy. Findings are expected to reveal elevated sulphate and calcium impurity levels requiring processing before food-grade application. Results contribute to economic mineral characterisation data for the Lake Chad basin and support the formalisation of artisanal salt mining in the North East geopolitical zone. Keywords: rock salt characterisation, Borno State, sodium chloride, Lake Chad, mineral analysis