During three seasons of excavation at Memphis, Egypt, 350 copper alloy objects were recovered, dating to the fifteenth-twelfth centuries BC. Most of these objects have a remarkably thick, soft, pale green corrosion layer that does not resemble any of the previously described corrosion products. After the first season of excavation this corrosion product was identified by X-ray diffraction studies as the complex copper phosphate, sampleite, NaCaCu5(PO4)4C1.5H2O. The identification was confirmed by studies of naturally-occurring mineral specimens of sampleite and by additional analytical studies of the corrosion product itself. The mineral has not previously been fully authenticated as a corrosion product of ancient copper alloys.
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Fabrizi et al. (1989) studied this question.