DETECTING FORGERIES AMONG ANCIENT GOLD OBJECTS USING THE U,Th–4He DATING METHOD*

Forgeries of ancient gold objects are prevalent in almost every collection and some public exhibitions in the past have been exposed as containing forgeries to an embarrassing extent. This situation comes from the fact that it is sometimes impossible to unequivocally recognize forgeries based on their patina or manufacturing and decoration characteristics. We demonstrate that for 13 ancient gold objects the time of their last melting process can be estimated using the U,Th–⁴He dating technique. The extremely small quantities of radiogenic ⁴He found, due to the young age and small sample size, require the use of a specially designed ultrasensitive mass spectrometer. We show that the proposed method is a powerful, and the only, quantitative tool in archaeometry for discriminating between fake and genuine ancient gold objects.     

TECHNOLOGY OF PRODUCTION OF GHAZNAVID GLAZED POTTERY FROM BUST AND LASHKAR‐I BAZAR (AFGHANISTAN)

Fifteen fragments of glazed pottery were studied by scanning electron microscopy coupled with energy‐dispersive X‐ray analysis (SEM–EDS). The fragments, dated from between the 11th and the 12th centuries, are part of a group excavated at ancient Bust and Lashkar‐i Bazar (southern Afghanistan) and belonging to the International Museum of Ceramics in Faenza. All the samples are characterized by highly calcareous bodies, and all of them but one is coated with a transparent lead glaze; the last fragment is, instead, coated with a turquoise opaque lead–alkali glaze. With three exceptions, the studied fragments show underglaze decorations featuring white, red, green or black motifs applied on to a white, red or black engobe; one of the remaining glazes is applied on to a monochrome white slip and the other two directly on to the ceramic body. Optical microscopy and SEM images show that engobes and decorations were obtained by deposition of differently coloured clayey slips, the composition of which was characterized by EDS analyses. In particular, black engobes and decorative motifs were obtained by recourse to manganese and iron compounds or to chromium, magnesium and iron compounds; it appears that both possibilities could be exploited for obtaining different decorative motifs on the same object.