The petrographic analysis of the marble is an important part of the effort to preserve a Roman sarcophagus. The studies were initiated to provide physical confirmation of the provenance and also to locate a source for analogous modern samples necessary for further tests. Isotopic ratio analysis and examination of the original marble strongly suggest that it comes from the Greek island, Thasos. Both the ancient sample and marble recently quarried from the island for comparison were found to be dolomitic, essentially granoblastic, with very limited porosity and a high degree of water repellence. The acquisition of modern samples with properties virtually identical to the ancient stone had made it possible to design a testing protocol that will determine the rate of surface loss, the effectiveness of proposed treatments and the requirements for optimum exhibition of the artifact in the future. -- SCMRE