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High
purity copper artefacts dated to the Eneolithic period from
Romania have been grouped by cluster analysis in order to
establish the geological nature of raw materials used by the
early metalworking in this area. The chemical composition
in major and trace elements has been determined by ICP-AES.
Trace elements used as markers for native copper have been
analysed and grouped in order to distinguish between made
techniques of the heavy implements.
Here we discuss some aspects regarding the number of "real"
clusters and methods of validation. A subset of samples of
known origin that was "a priori" supposed to group
together have been introduced in order to monitor the clustering.
Additionally, principal component analysis has been used to
supplement the cluster analysis. Analytical groups obtained
by cluster analysis have been displayed in two dimensions
by using component plots. The dendrograms were displayed directly
above the associated component plots.
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