Bekhen stone artifacts in the Egyptian Antiquity Museum of Turin (Italy): a mineropetrographic study.

A recent project to investigate the stony handcraft preserved in the Egyptian Antiquity Museum of Turin has been undertaken with the aim to study the stones of Egyptian finds, by a geological and minero-petrographical view point, in order to enhance the value of this artistic heritage and to set the base for its best conservation. It is the first systematic and scientific study performed on the stone finds of this museum. This paper regards the minero-chemical study of three black stony sarcophagi dated from Saitic to Roman age. By optical and scanning electron microscope observations the sarcophagus stones resulted a metagreywacke with irregular clasts of various nature whose mean size is from 100 to 200 micrometer. The main clasts are represented by quartz, albite, chlorite, epidote, white mica and opaques dispersed in a fine-grained sericitic matrix. Subordinately, clasts of biotite, sphene, ilmenite and apatite also occur. No oriented foliation is evident. The described features suggest the stone is represented by a former sedimentary rock which underwent a metamorphic re-crystallisation at low temperature but relatively high pressure for the phengite composition of white mica in the matrix. According to a petrographic and minero-chemical comparison between the sarcophagus stone samples and rock samples collecte in a well-known ancient quarries located in the Eastern Egypt Desert, it has been possible to attribute the sarcophagus stone material to the "Bekhen Stone", a precious natural stone used in the Ancient Egypt up to the Roman Empire. The assignment of the well-preserved stony sarcophagi to the Bekhen Stone makes the Egyptian Antiquity Museum of Turin one of the most valuable collection, all over the world, for precious stones in archaeological field.