#TITLE_ALTERNATIVE#

• Main Author: NIKEN LARAS SHINTA (NIM : 12011041); Pembimbing : Ir. Nurcahyo Indro Basuki, M.T., Ph.D
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/20350
• Institution: Institut Teknologi Bandung

Low sulfidation epithermal deposit in Gunung Pongkor is an ore deposit which gold and silver are the main commodity. In this location, research of the quartz textures in each quartz facies of the veins was being studied. The facieses are disseminated at five vein locations, that are, from northeast – southwest, Pasir Jawa, Gudang Handak, Ciguha, Kubang Cicau, and Ciurug. The distribution of the facieses was being determined in this research. Besides, the mineralization processes of each facies and the change of quartz veins formation condition were also determined by integrating the data of quartz textures, grade of Au and Ag, mineralogy, temperature, salinity, and also sulfide content of the veins. In this research, Au and Ag assay by using DIBK method, thin section analysis, polished section analysis, and hand specimen analysis directly were being undertaken. <br /> <br /> <br /> There are five quartz facieses that are representated by a certain mineral assemblage. From the oldest to the youngest, they are carbonate-quartz (CQ), manganese oxide-quartz (MOQ), banded opaline quartz (BOQ), grey sulfide quartz (GSQ), and late geodic quartz (LGQ). The youngest facies, LGQ, is not mineralized. The quartz facieses of the veins distribution shows a trend that the younger quartz facieses are more dominant to the southeast area. Based on the grade of Au and Ag data, the younger quartz facies, the higher grade that it has. So, it means that to the southeast area, the grade of Au and Ag is increased. Based on the presence of the quartz textures in each mineralized facies, the main mechanism of the gold deposition is boiling. Crustiform and colloform are the main textures of boiling manifestation which were formed during the mineralization process. Therefore, both of textures can be used as the indication of high grade of Au and Ag. During the formation of quartz facieses of the veins, it was expected that from the first until the fifth phase, the decreasing of hydrothermal fluid temperature and CO2 content happened. Moreover, the increasing of sulfide content in hydrothermal fluids also happened that caused the grade of Au and Ag also increased.