Monday, August 5, 2013

Collaborating with Osteoarchaeologists

A cluster of small finds was excavated recently, including some bronze fragments and a green bone. In order to further investigate the possible relationship between these objects, Kaman Kalehöyük conservators sought the expertise of Cheryl Anderson, a PhD student in anthropology at the University of Nevada Las Vegas. Cheryl began by explaining how human bones differ from other mammals and concluded that the bone was a rib of a medium size mammal like a goat or a dog. 

Buried bone often takes on the color of the surrounding soil; conservators are able to elaborate on the scientific aspects of this particular phenomenon. The green color of many excavated metals can be attributed to copper corrosion products (such as copper carbonates, copper hydroxides, copper sulfates, etc.), which form on the surface as copper alloys deteriorate.  Many of these minerals are excellent colorants and certain compounds, like malachite (Cu2CO3(OH)2), have been used as green pigments in paints from ancient times. Because it was buried near these bronze fragments, the bone was stained by the green corrosion products as the copper alloys deteriorated.

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