A combination of the following analytical procedures is applied: petrography, analysis of the stable isotopes of C and O, trace element chemistry, and analysis of micro-inclusions.
For the analysis of stable isotopes of O and C, an amount of sample in the range of a few mg is required. However, extremely small samples in the order of about 1 mg taken from surfaces imply the risk of wrong results because of appreciable modification of the isotope composition. Therefore, a well-considered sampling is a prerequisite. Additional variables are obtained by trace element chemistry. In contrast to the outsized amount of stable isotope data, the information on other chemical parameters of ancient white marbles is rather moderate. In this context, it is important to mention that those elements that are incorporated into the carbonate lattice (Mg, Fe, Mn, Sr, and Zn) exhibit a fairly homogeneous and consistent distribution and can advantageously be used to discriminate between different types of white marbles. The analysis of micro-inclusions, based on the “crush and leach” analysis of extractable total dissolved solids - TDS - from marbles and carbonate rocks, are used. These solutes occur basically in very small fluid-filled cavities, the so-called fluid inclusions, which can be found in all marbles and are usually relatively homogeneous in composition. Petrography is applied systematically; if the size of the sample is sufficient, thin sections for microscopic investigations are prepared.
Photo: The Asenovgrad quarries near the Roman Philippopolis (Lovcation: Ravdin 1) (© ÖAW-ÖAI/V. Anevlavi)