| Abstract |
Geothermal is an alternative energy that has a high temperature and in certain temperature and preassure the surrounding rocks become alterated, in this alteration zone usually the type and characteristic of geothermal system can be decided. Therefore in order to know further about the geothermal system a certain tool is needed to investigate the alteration rocks. Petrography is a branch of petrology that studies the characteristics of rocks in a microscopic scale. Due to the microscopic scale, this method can describe provenance, zone of alteration, mineral assemblages, and characteristics of rocks more specific and detailed than macroscopic scale. In petrography there are many techniques that can be used based on the purposes of doing the petrographic analysis such as thin section preparation, X-Ray Diffraction, Scanning Electron Microscope, GPAC and etc; to make a better result and a higher accuracy data these techniques can be combine together. In geothermal exploration, the petrographic analysis plays an important role in determining the potential resources. A petrographic analysis can be use in many ways like describing core samples from an exploration well, using a scanning electron microscope to characterize the fracture surfaces from microstructures or doing X-ray diffraction to identify exact mineral assemblages of a rock, and thin section to confirm the alteration minerals and type of rocks. |