*Mengnjo jude WIRMVEM¹、Takeshi OHBA¹、Tasin godlove BAFON²、Brice tchakam KAMTCHUENG³、Eldred tunde TAYLOR⁴、Asobo nkengmatia elvis ASAAH⁵、Engome regina WOTANY⁶、Seigo OOKI¹、Wilson yetoh FANTONG⁷、Samuel ndonwi AYONGHE⁶ (1.Department of Chemistry, School of Science, Tokai University、2.Compagnie Miniere Du Cameroun、3.Graduate School of Science and Engineering for Education, University of Toyama、4.IEMQC, Njala University、5.Department of Earth & Planetary Sciences, Tokyo Institute of Technology、6.Department of Environmental Science, Faculty Science, University of Buea、7.Institute of Mining and Geological Research, Cameroon)