Evaluation of Raman Spectroscopic Geothermometry of Graphitic Carbon as a Mineral Exploration Tool. A Case Study of the San Sebastian Au-Ag Mine, Durango, Mexico
Abstract
While visually similar to graphite, graphitic carbon is disordered rings of carbon whereas graphite is the pure-carbon crystalline form. As graphitic carbon is heated, it undergoes an irreversible graphitization process which can be observed using Raman spectroscopy and determine the maximum temperature that a rock was exposed to. Samples of sedimentary rocks, taken from the Au-Ag San Sebastian mine in Durango Mexico, containing graphitic carbon located from positions in contact with mineralized veins were used in developing a low-cost protocol for Raman spectroscopic analysis of drill core. The samples were cut and then polished to provide a smooth surface, so that the Raman collection could be conducted on the drill core directly. When plotted on longitudinal sections, the temperature distribution identified potential up-flow zones where mineralizing fluids were focused. In conclusion Raman spectrometry of graphic carbon is a rapid, cost-effective geothermometer and shows considerable promise as an exploration tool.