Physico-Chemical and Mineralogical Characteristics of Obajana Marble Deposit, Central Nigeria: Implication for Economic Appraisal

Abstract

Marble is one of such minerals occurring in Obajana area that can be exploited for various uses other than cement production that the area is well known for. Hence, the continuous investigation into its economic viability can never be over emphasized. The physical, geochemical and mineralogical attributes of Obajana marble was investigated for the purpose of its economic potential. Obajana marble is closely associated with meta-sedimentary and granitoid rock assemblages of the Precambrian Lokoja - Jakura Schist Belt of central Nigeria. Thirty (30) representative samples were collected from the bench crest and bench trough from the 3 pits investigated based on variation of colour, texture and structure during field investigations .Physical properties were determined for while optical microscope and X-ray fluorescence techniques were used to discern mineralogical and chemical composition of the samples. The colour ranges from whitish to dark colour minerals, with traces of brownish colour and are very attractive based on physical look. Physical parameters for the marble indicated varied compressive strength (13.84 – 93.60 MPa), hardness (3.05), specific gravity (2.72), colour brightness (83) and pH (8.3). Chemical data showed pit 1, CaO (50.30 - 53.99%); MgO (0.00 -0.38 %); pit 2, CaO (48.31 - 51.87 %); MgO, (0.41 - 1.63%) and pit 3, CaO (49.39 - 52.93%); MgO (0.06 - 1.19 %) and in general reveal calcitic marble by virtue of the CaO : MgO ratios of the marble bodies. Also, mineralogy reveals that samples are composed mainly of calcite, with minor amounts of dolomite, quartz, magnesium oxide and iron. Appraisals of the functional potential of the marble based on physical, geochemical and mineralogical characteristics indicate that Obajana marble is suitable for cement feedstock, iron and steel fluxes, fillers in paints and paper making and as extenders in the manufacture of glass as well as useful in water treatment.