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To identify probable age and origin of ceramic, stone and tile objects.
Beneath any surface artistry, a porcelain bowl or marble statue is basically clay or rock. And these 'man-made rocks' can be geologically analyzed just like any other rock. Using a technique called thin-section petrography, investigators can learn where, when, and how stone and clay artifacts were made.
The method is also used in conservation research, and to establish authenticity. For authentication, the petrographic profile of the artifact is compared to known quarries and clay pits of the time, and also against similar pieces of known provenance.
But the evidence is not necessarily conclusive, as in the case of The Getty Kouros bought with a dubious provenance in 1983. [Hint: the provenance was disproved as it used a postal code devised in the '70s.] Scholars voiced concerns about stylistic flaws, and dubbed the statue a forgery.
The Getty responded with a detailed petrographic analysis, which proved that the statue's surface had suffered dedolomitization, a change that happens naturally, over hundreds of years.
Things were quiet until 1990, when the torso of another kouros turned up - a stylistic twin to The Getty kouros - and a known forgery. The museum began a comparative analysis. Meanwhile, a group of scientists was proving that a dedolomitized marble surface could be created, in about 3 months, by applying potato mold.
In 1992, an international colloquium sponsored by The Getty could not reach a conclusion. So for now, the museum describes the kouros as, "Greek, about 530 B.C., or modern forgery."