The Rare Earth Elements in Grobogan Mud Volcanoes, Indonesia: Alternative Mineral Resources for Advancing the Green Energy Technology

The Indonesia is one of the prospective countries for rare earth element (REE) exploration.The study of rare earth elements in Indonesia is growing enormously.Currently the exploration is focused on the granitoid rock that widely distributed in Sumatera, Sulawesi, Kalimantan and Papua.The famous one is potential sources of REE come from residual tin mining in Bangka Island, Sumatera.Meanwhile the potential of REE abundance in mud volcano area is rarely studied and analyzed.The objective of this paper is to present the potential of REE in the Grobogan mud volcano, which has not been done before.As REE is one of the very important materials in green energy technology.Mud volcano is still considered as the sources of disaster with less impact compared to traditional volcanoes.Mud volcano is believed to have no benefits for human life.This study was done to show the REE contents from the mud sample in study area.The sample was taken from the fresh mud of eight mud volcanoes in study area.These mud volcanoes appear on the surface due to Rembang-Madura-Kangean fold and thrust belt activity.Among the 17 rare earth elements, 16 of them recorded in mud sample, only Promethium (Pm) was not recorded in this study.The 5 most common rare earth elements that present in the mud sample are Scandium (Sc), Cerium (Ce), Lanthanum (La), Neodymium (Nd), and Yttrium (Y).SEM analysis was done to the mud samples show that the mud samples are dominated by Smectite-Illite clay mineral.Clay mineral can be the sources of the REE abundances in the mud volcanoes.