Neutron activation analysis applied to assemblage problems in fragmented marble sculptures

One of the major problems encountered in assemblage work on fragmented marble sculptures is determining if two pieces were originally joined together when there are no remaining material links between the two. This work deals with solving this problem by using Neutron Activation Analysis techniques. Samples from a block of sculpture grade Georgian marble were analyzed. The following trace elements were identified on the basis of their gamma ray energies and their half-life studies: 165Dy, 155Sm, 152Eu, 56Mn, 24Na, 85Sr, 51Ti, 80Br, 27Mg, 52V, 42K, 28Al, 46Sc, 141Ce, 198Au, 140La, 122Sb, and 124Sb. The next step in this work was to determine whether the trace elements, which were originally trapped in the marble during metamorphosis, formed concentration patterns which extended over short distances in the stone. A block of sculpture grade Colorado marble was cut into a number of slices and these slices were analyzed for the trace elements they contained. The concentration patterns formed by these impurities were followed through successive layers of the stone. The ability to follow these ''fingerprint'' concentration patterns over short distances in marble was further tested by analyzing two adjoining segments of a Roman wall relief at the J. Paul Getty Museum in Malibu, California. The trace impurity ''fingerprints'' were successfully matched between the wrist and hand segments of this piece