Groundwater resources of the Cretaceous Gundumi Formation and the underlying crystalline basement rocks have always been the source of water supply in Daura. Records of thirty-one boreholes drilled in the area between 1959 and 1996 were reviewed to deduce the hydrogeology of the area. The lithology of the study area obtained from strata logs and geophysical survey comprises decomposed crystalline rocks overlain by basal conglomerate, loosely cemented gravely sandstone, ferruginous sandstone and clay horizons, capped in places by laterite or silty fine sands. The area is divided into the northern and southern wellfields with average thicknesses of the Gundumi Formation of 50 m and 35 m, respectively. The average yield of the productive boreholes is 4.1 lps. The aquifer of the Gundumi Formation in the Daura area has low to moderate groundwater potential. However, the low capacities of the production boreholes are adequate to sustain the domestic water requirements of the population. Borehole site selection should be based on geophysical investigation, while the drilling rig should be capable of both rotary and downhole-hammer drilling. The borehole completion materials should be resistant to corrosion because of the low pH of the groundwater. The quality of the groundwater is generally suitable for domestic uses, though aeration or lime treatment may be necessary in some cases because of the slightly acidic nature of the groundwater. Contribution/Originality:This study is one of the very few studies which have investigated the aquifer properties, groundwater potential and quality in the Daura area of Katsina State, Nigeria using geophysical, borehole and physicochemical data, in a view to appraise the groundwater resources, improve borehole siting, construction and development in the area. the chemical composition is within tolerable limits (Offodile, 1992). In order to meet the domestic, agricultural and industrial needs of the people, the search for potable water has often been extended into the subsurface.

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The mineralogical compositions of the Gerinya claystone, Patti Formation, Southern Bida Basin, Nigeria, were investigated to infer their sedimentological process and industrial application. Mineralogical analysis of the claystone was carried out using the X-ray diffraction (XRD) method. The diffractogram peaks aided the identification of the clay and non-clay minerals in the study area. The XRD showed kaolinite as the major clay mineral with compositions ranging from 10.8 - 67.6 wt%. The non-clay minerals were quartz, anatase, diopside, goethite, hematite, rutile, muscovite and micro-cline. Among the non-clay minerals, quartz had the highest percentage mineralogical composition of 21.2 to 83.4 wt%. The mineral assemblage is typical of a hot and humid climate where chemical alteration and hydrolysis of silicate minerals are severe. The sediments are of mafic and felsic crystalline rocks origin. The sediments are of low energy floodplain/interchannel depositional environment. The Gerinya claystone vary from low to high porosity and very low to low permeability. The claystone can be used as clay liners and as raw material for ceramic production. The application of the claystones in fertiliser production will require some processing. The clay-stone can be used for haemorrhage control in the pharmacological/medical sector. Although, the ingestion of the clay-stones could lead to dental damage and possible perforation of the sigmoid colon in the gastrointestinal tract.

Seventy borehole data were used to appraise the groundwater resources of the sedimentary and Basement Complex rock terrains of Ogun State, Nigeria. Borehole depth, static water level, discharge and drawdown were evaluated to determine the hydrogeological and hydraulic properties of the aquifers. Specific capacity of the boreholes was estimated at one hour using discharge and drawdown values. Most boreholes in the sedimentary terrain explored shallower aquifers of < 100 m, while most boreholes in the Basement Complex rock terrain explored deeper aquifers > 100 m. The sedimentary rock aquifers had thinner groundwater storage of 65.28 m and average borehole yield of 43.51 m 3 hr −1 , while the Basement Complex rock aquifers had thicker groundwater storage of 95.02 m and average borehole yield of 5.53 m 3 hr −1 . The average efficiency of boreholes in the sedimentary and Basement Complex rock terrains were 0.66 and 7.14 m 2 hr −1 , respectively. Boreholes within Basement Complex rocks had higher efficiency than those within sedimentary rocks. Adequate groundwater occurs in the sedimentary and Basement Complex rock terrains for domestic, industrial and agricultural purposes. The groundwater is weakly acidic with small amount of TDS, hence falls within the fresh water category. The groundwater is not potable but could serve domestic and general purposes.

The quality of groundwater from twenty (20) hand-dug wells around the Mando and Rigasa areas, Northwestern Nigeria was evaluated in this study. Physico-chemical parameters like pH, EC, TDS, temperature, Na+, Ca2+, K+, Mg2+, Fe2+, Cl-, HCO3 -, NO3 -, SO4 2- and faecal coliform count were analysed. The degree of compliance of the various parameters with international guidelines for drinking water quality were determined and the groundwater classified. Comparison of the results of physico-chemical analysis with the NSDWQ and WHO guidelines revealed that most of the parameters in the groundwater had 100 % compliance except for pH, Mg2+, NO3 -, K+ and Fe2+ with percentage compliance of 80, 90, 75, 70 and 40, respectively. This indicates that some of the groundwater samples are not suitable for drinking purpose. Groundwater quality map based on the Water Quality Index values for the various groundwater sample showed that most parts of the study area have excellent groundwater quality. The faecal coliform bacteria count ranged from 0 CFU/100 ml to too numerous to count. Only two (2) groundwater samples (10%) complied with the 0 CFU/100 ml guidelines of the NSDWQ and WHO, while the rest eighteen (18) groundwater samples (90 %) have faecal coliform bacteria count above the recommended value. Most of the groundwater samples are not suitable for drinking based on the faecal coliform count. The groundwater samples are suitable for agricultural purposes based on the SAR, RSC and PI classifications. The groundwater in the study area is dominated by Na-Cl and CaHCO3- type facies water.