Citation: Syaeful, H.; Ciputra, R.C.; Adimedha, T.B.; Sumaryanto, A.; Sukadana, I.G.; Indrastomo, F.D.; Pratiwi, F.; Sucipta, S.; Pratama, H.A.; Mustika, D.; et al. Radiometric Signatures of Gold Mineralization Zone in Pongkor, West Java, Indonesia: A Baseline for Radiometric Mapping Application on Low-Sulfidation Epithermal Deposit. Resources 2024, 13, 2. https://doi.org/ 10.3390/resources13010002 Academic Editors: Jian Cao and Zhiyong Gao Received: 13 November 2023 Revised: 13 December 2023 Accepted: 18 December 2023 Published: 21 December 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). resources Article Radiometric Signatures of Gold Mineralization Zone in Pongkor, West Java, Indonesia: A Baseline for Radiometric Mapping Application on Low-Sulfidation Epithermal Deposit Heri Syaeful 1,2, * , Roni Cahya Ciputra 1 , Tyto Baskara Adimedha 1 , Agus Sumaryanto 1 , I Gde Sukadana 1 , Frederikus Dian Indrastomo 1 , Fadiah Pratiwi 1 , Sucipta Sucipta 1 , Hendra Adhi Pratama 1 , Deni Mustika 1 , Kurnia Setiawan Widana 1 , Susilo Widodo 3 , Muhammad Burhannudinnur 4 , Ildrem Syafri 2 and Bronto Sutopo 5 1 Research Center for Nuclear Fuel Cycle and Radioactive Waste Technology, Research Organization for Nuclear Energy, National Research and Innovation Agency (BRIN), South Tangerang 15314, Indonesia; roni010@brin.go.id (R.C.C.); tyto001@brin.go.id (T.B.A.); agus029@brin.go.id (A.S.); igde001@brin.go.id (I.G.S.); fred002@brin.go.id (F.D.I.); fadi005@brin.go.id (F.P.); suci002@brin.go.id (S.S.); hend031@brin.go.id (H.A.P.); deni010@brin.go.id (D.M.); kurn009@brin.go.id (K.S.W.) 2 Faculty of Geological Engineering, Padjadjaran University, Bandung 45363, Indonesia; ildrem@unpad.ac.id 3 Research Center for Safety, Metrology, and Nuclear Technology, National Research and Innovation Agency (BRIN), South Tangerang 15314, Indonesia; susi001@brin.go.id 4 Geological Engineering Department, Trisakti University, Jakarta 11440, Indonesia; burhan@trisakti.ac.id 5 Geomin Unit of PT. Antam Tbk., Jakarta 12530, Indonesia; bronto.sutopo@antam.com * Correspondence: heri021@brin.go.id Abstract: Radiometric mapping could play a prominent role in locating the host rock or alteration that leads to gold mineralization. Nevertheless, in low-sulfidation epithermal gold deposits, the radiometric signatures have to be priorly characterized due to their geometry. It is comprised of a small ore vein system within the large alteration zones. The Pongkor gold mine is a low- sulfidation epithermal deposit and was selected for this purpose. The method started with the surface identification of radiometric signatures on altered and unaltered rocks near Pongkor using portable spectrometers. They are followed by the characterization of the underground mining front, which is comprised of different types of veins and host rocks. The results show that the altered rocks were characterized by a high K% and a low eTh/K ratio. Vice versa, the mineralized veins show low radioelement concentrations. Following the characterization of the geometry of alteration zones and mineralized veins, a study of the relationship between radioelements detected by radiometric mapping and gold pathfinder elements was conducted. Gold pathfinders of Mn, Fe, Zn, As, and Pb were selected for correlation studies with the radioelement. The pathfinders and radioelements were more significantly correlated in veins compared to the host rock. Based on this study, radiometric mapping has the potential and benefit of being applied in the exploration of low-sulfidation epithermal gold deposits. An alteration zone could be delineated by K or eTh/K as an anomaly indicator, and the vein bodies could also be delineated using low K or eTh as an anomaly indicator. Keywords: radiometric mapping; gold deposit; pathfinder; Pongkor; low-sulfidation epithermal 1. Introduction The radiometric mapping measures the abundance of K, U, and Th, naturally oc- curring radioactive materials (NORM), on Earth’s surface. The method is best executed with a multispectral sensor, referred to as gamma spectrometry, so the signature of the radioelement can be separately recorded and allow further analysis. The measurements can map and characterize different rock units based on the varying concentrations of these radioelements [1,2]. The method is prevalent, practical, and effective for detecting thorium and uranium anomalies in exploration. Radiometric mapping that has been carried out in Resources 2024, 13, 2. https://doi.org/10.3390/resources13010002 https://www.mdpi.com/journal/resources