Shale exposed around Dange northwestern, Nigeria was studied. The aim was to determine the grade, quality and usability of the shale as drilling mud using its physico-chemical and the rheological characteristics. Sixty-one (61) samples were collected from exposed sections and pits. Major elements such as SiO2, Al2O3, MgO and CaO were determined. X-ray diffraction method was employed for the qualitative identification of the minerals in the shale. Cation Exchange Capacity and Exchangeable

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... were determined using the Methylene Blue Absorption and Ammonium Acetate Saturation Methods respectively. Grain-size distribution and Atterberg Limits tests were also conducted. Apparent Viscosity, Plastic Viscosity and Yield point were calculated from readings obtained on a multi-speed Fann viscometer. The dominant clay mineral observed is smectite (71%) implying good expansive potential. Dominant oxides were SiO2 (42.60-57.50%), Al2O3 (12.00-16.70%), CaO (0.43-12.50%). Exchangeable cations obtained were Na+ (0.48-6.67), Ca2+ (14.03-34.50) and K+ (0.42-1.95) meq/100g clay. Liquid and plastic limits ranged from 69.40-86.00% and 30.10-36.10% respectively giving a Plasticity Index of 39.40-52.60%. The samples plot close to Ca-montmorillonite on the clay identification chart. The viscosity increased on addition of 7-10% sodium carbonate. It has good sodium exchange potential. In the natural state, it does not meet the API/OCMA specifications. However, its rheological properties improved significantly on treatment with sodium carbonate thus confirming its suitability as raw material in drilling mud.