Authenticity brass

An inscribed thick plate of brass attributed to the landing, in 1579, of Francis Drake on the coast of California, is retained in safekeeping at the University of California, Berkeley. Since its discovery, in the San Francisco Bay area in 1936, however, there have been doubts about the authenticity of the plate, although an early chemical study had apparently confirmed its authenticity. Regardless of this initial study, doubts about the origin of the plate persisted, and a new study, based on the composition of the brass as determined by neutron activation, X-rays fluorescence, and atomic absorption analysis was initiated to reevaluate the earlier authentication of the plate. The results of this study were then compared with the composition typical of brass from Drake s time as well as from modem brass, and it was then concluded that the plate was probably made during the latter part of the nineteenth century or the early years of the twentieth century (Hedges 1979). 

Pollard, A.M. (1983a). Authenticity of brass objects by major element analysis Paper presented at Symposium on Archaeometry, Castel Dell Ovo, Naples, 18th-23rd April 1983. 

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