Getty Kouros - Archaeometry

Archaeometry

The Getty commissioned two scientific studies on which it based its decision to buy the statue. The first was by Norman Herz, a professor of geology at the University of Georgia, who measured the carbon and oxygen isotope ratios, and traced the stone to the island of Thasos. The marble was found to have a composition of 88% dolomite and 12% calcite, by x-ray diffraction. His isotopic analysis revealed that δ18O = -2.37 and δ13C = +2.88, which from database comparison admitted one of five possible sources: Denizli, Doliana, Marmara, Mylasa, or Thasos-Acropolis. Further, trace element analysis of the kouros eliminated Denizli. With the high dolomite content Thasos was determined to be the likeliest source with a 90% probability. The second test was by Stanley Margolis, a geology professor at the University of California at Davis. He showed that the dolomite surface of the sculpture had undergone a process called de-dolomitization, in which the magnesium content had been leached out, leaving a crust of calcite, along with other minerals. Margolis determined that this process could occur only over the course of many centuries and under natural conditions, and therefore could not be duplicated by a forger.

In the early 1990s, the marine chemist Miriam Kastner produced an experimental result which cast doubt on Margolis’s thesis by artificially inducing de-dolomitization in the laboratory, a result since confirmed by Margolis. However, although this does admit the possibility the kouros was synthetically aged by a forger the procedure is a complicated and time-consuming one. The unlikeliness of a forger using such experimental methods in what is still an uncertain science has prompted the Getty’s antiquities conservator to remark "when you consider a forger actually repeating the procedure you begin to leave the realm of practicality”.