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Lead

Submitted by curator on Fri, 10/16/2015 - 11:01

Like the arsenic, the lead in all the Gawra copper-based artifacts in this study most likely derive from the original copper ore, its variation (from near-trace levels to around 1.9%) simply reflecting differences in the conditions of smelting of the original copper ore (Tylecote et al. 1977). Lead’s tendency to segregate within the microstructure of a bronze means that, at levels of about 1% or more, its distribution within an artifact can be quite varied. Only seven among the 110 copper-base artifacts from the site’s Levels VIII through IV (circa 3750 B.C.–2100 B.C.) that have a significant lead content (Pb >0.5%):

Level VIII (among 4 artifacts):
None

Level VII (among 16 artifacts):
Boss with perforations (31-52-367: Pb, 0.63%)

Level VI (among 74 artifacts):
Butt (31-52-267: Pb, 1.9%)
Awl (31-52-235: Pb, 0.90%)
Axe, in holder (31-52-251A: Pb, 0.63%)
Chisel (31-52-238: Pb, 0.55%)

Level V (among 12 artifacts):
Snake (31-52-45: 0.62%)
Toggle pin (31-52-44: Pb, 0.54%)

Level IV (among 4 artifacts):
None