Mineralogical and Geochemical Characterization of Gold Bearing Quartz Veins and Soils in Parts of Maru Schist Belt Area, Northwestern Nigeria

Epigenetic, N-S, NNE-SSW quartz veins crosscut metapelites and metagabbro in Maru area. The objectives of this work were to study field, mineralogy, and geochemical characteristics of gold bearing quartz veins and soils. Euhedral and polygonal magnetite with hematite constituted the major ore minerals. Quartz occurred as main gangue phase with appreciable sericite and chlorite. The mineralogy of soil retrieved from twelve minor gold fields examined with X-ray diffraction is quartz ± albite ± microcline ± muscovite ± hornblende ± magnetite ± illite ± kaolinite ± halloysite ± smectite ± goethite ± vermiculite ± chlorite. The concentration of gold in quartz vein varies from 10.0 to 6280.0？ppb with appreciable Pb (3.5–157.0？ppm) and ΣREE (3.6 to 82.9？ppm). Gold content in soil varies from < to 5700.0？ppb. The soil is characterized by As ± Sb gold’s pathfinder geochemical association. Multidata set analysis revealed most favourable areas for gold. Possibility of magmatic fluids as part of ore constituents is feasible due to presence of several intrusions close to quartz veins. Based on field, mineralogical, and geochemical evidences, ore fluids may have been derived from fracturing, metamorphic dewatering, crustal devolatilization of sedimentary, gabbroic protoliths, and emplaced in an orogenic setting. 1. Introduction Precambrian rocks within and around Maru Schist belt host some quartz veins that are gold bearing. The gold deposits were heavily mined during the colonial era approximately before 1960 and after that period by artisanal miners. General descriptive information on gold mineralization in Maru schist belt has been documented [1–3]. Gold occurs primarily in quartz veins and as placers in soil (eluvial) and stream sediments (alluvial). The quartz veins containing gold occur in association with metamorphosed rocks ranging in composition from semipelitic to pelitic and mafic. Primary gold mineralization produced chemical signature in the overburden and surrounding soil probably through weathering processes. Weathering processes provide samples (soils and stream sediments) that yield data on local hidden mineralization or on the potential existence of major or minor mineralization in a wide region. The residual soil is the geochemical sample that is often used to detect the location of hidden mineralization once a zone of economic interest is localized [4]. Migration of groundwater provided chemical response at the surface. This process produces elemental dispersion pattern [5]. Most of these dispersed elements (e.g., Cu, Ag, Zn, Cd, As, Bi, Pb, Sb,