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Below is a photograph of the spot where the sample was found. The white line indicates where the thin section was made. The smooth layer on the picture is about 2.0 centimetres wide and 1.3 centimetres deep. The sample was carefully cut into two parts and a thin section was taken for analysis in the JXA-8600 Pioneer microprobe. Several points were measured on the inside of the sample and on the smooth surface. The sample as photographed by the microscope shows two distinct regions: the surface layer and the body stone. There is a less-distinct intermediate area between the two that seems to show a transition from stone body to surface layer. Samples from all three regions were subjected to detailed analysis. eS ae This microscope photograph shows the vitrified surface of the stone. The line at the bottom measures 21 micrometres in length. composition for limestone. High levels of calcium, carbon, oxygen and minor trace elements are the constituents of limestone. This is not unusual, since the Sacsayahuamén archaeological park is considered to be a karst landscape, as recognised by the University of Cusco. Many cave systems are created in limestone bedrock, and the sample is from this sort of cave. However, this cave was worked on by people in the past, as is clear from the photographs above. The vitrified surface of the stone shows a very different spectrum of elements compared to the limestone body. The glaring difference is that silicon is the predominant ————, component, with much higher concentrations. The trace elements of aluminium and magnesium are also significantly higher than in the body of the stone. Oxygen is present in double the amount found in the body sample. The quantities of calcium and carbon are much lower an in the body sample. The silicon, aluminium and magnesium content seems to indicate that a material was added to the surface of he stone. The oxygen may have been part of this matter or it may have been introduced as part of oxidation during an aerobic heating process. This could have been during the formation of silicate SiO2). Analysis of the intermediate region between the surface and the body of a he stone shows a gradation of compositions. This is a surprising result. It implies that either the le’s surface layer. 5 surlace laye surface layer was somehow ground 62 * NEXUS This spectral analysis shows the composition of the sample’s surface layer. AUGUST - SEPTEMBER 2012 www.nexusmagazine.com