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.

Melangí¨ Complex of Ciletuh Area, West Java, Indonesia is located at 106 ° 23 '38.9 "- 106 ° 25' 27.6" E and 7 ° 14 '27.6 "- 7 ° 12' 46.2" S. This area has unique geological features where the Early Cenozoic uplifted subduction rocks such as ophiolites and metamorphic rocks are exposed. This study aimed to determine the condition of the stratigraphic position and geological structure of metamorphic rock unit in the field, to find out the metamorphic facies and their evolution, to know the parental rocks (protoliths) of metamorphic rocks, and to interpret tectonic environments for the formation of metamorphic rocks based on stratigraphy, geological structure, petrography, and geochemistry. Study of literatures, geological mapping, petrology and geochemical analyses were used as methods of this research. The entire analysis is combined as a guidance in interpretation of petro-tectonic environment. Distribution of metamorphic rock outcrops found in several places, such as, Citisuk River, Cikopo River and Cikarikil River. Based on petrography analysis, metamorphic rocks types consist of schistose amphibolite, various type of greenschist, phyllite and quartzite. The protolith of metamorphic rocks in Ciletuh is quite diverse, namely metasediments such as pelitic, psammitic, calc-silicate sediment, and meta-igneous such as gabbro and basalt. The presence of epidote, chlorite, and calcite in schistose amphibolite show retrograde metamorphism process in lower temperature-pressures condition. The occurance of quartz and calcite vein in several samples was shown as an indication of hydrothermal alteration. Based on geochemical characteristics, the result showed that sedimentary source of metasedimentary rocks were derived from the volcanic arc environment. While, metabasalt rocks were originated from the Island Arc tectonic environment. According to the association, these metamorphic rocks were formed by regional metamorphism, as the result of subduction process and orogenic event. Thus, retrograde metamorphism indicates the lifting or accretion process that caused by subsecuent tectonic activity.

Coal quality is one of the key factors in determining the effectiveness of processing and utilization. Coal quality assessment involves analyzing physical and chemical aspects to determine its characteristics. Coal quality is also influenced by geological conditions at the mining site, which affect the quality and amount of carbon in the coal. To ensure consistency, it is necessary to implement coal quality control based on physical and chemical parameters from the mining process in the pit to storage in the stockpile. Analysis of the effect of total moisture and ash on the calorific value of coal is the purpose of this study. The method used is a ROM (Run of Mine) coal sample located at the stockpile location. The relationship between Total Moisture and the calorific value of coal shows a negative linear correlation where the influence value for a 1% increase in Total Moisture is -71.343 kcal/kg and so is between Ash and the calorific value of coal 1% increase in Ash is -82.588 kcal/kg, which shows a negative linear correlation. Total Moisture increases by 1%, reducing the calorific value of coal by 71 kcal/kg, and increasing Ash content by 1% reduces the calorific value of coal by 83 kcal/kg.

Rare earth elements (REEs) are essential materials for the manufacture of advanced technology. Secondary REE indications were found in alluvial and lateritic tin deposits within Southeast Asia Tin Belt. This study aims at the REE enrichment of weathering profiles underlain by Toboali Pluton of the main range S-type granite of this belt. Granite and weathering samples were collected and analyzed using XRF, ICP-MS/OES, XRD, SEM-EDX, and EPMA. The Chondrite-normalized REE patterns of granite in Toboali showed enrichment in REE with the highest value of 1,126 ppm. The Toboali Pluton is enriched in LREE and depleted in HREE. The enrichment of REE from the upper to lower horizon of weathering profiles was pointed out by the increase in REE values from a range of 156-188 ppm (horizon B) to 196-268 ppm (horizon C) in Toboali, and from a range of 230-330 ppm (horizon B) to 342-450 ppm (horizon C) in Air Gegas. These coincided with the presence of kaolinite with elevated REE and CeO2 in horizon C of weathering profile. Leaching test result proved that kaolinite plays a role in REE enrichment in the weathering profile through ion adsorption mechanisms in the Air Gegas. The weathering process of REE fluoro-carbonate (bastnäsite-(Ce)) and parisite-(Ce) in granite is believed to contribute in enrichment due to its high dissolution rate, which enhances kaolinite adsorption. In contrast, REE phosphates such as monazite-(Ce) and xenotime-(Y), because of their strong resistance and low solubility, are thought to be only slightly soluble, and most of these minerals remain in Toboali weathering products.