Lapis lazuli is a blue semi-precious stone widely used since the antiquity for the manufacture of precious objects and jewellery. It’s characterized by the presence of the mineral lazurite, giving the typical blue colour to the rock, traversed by gray-white or yellowish veins, due to the presence of various accessory minerals such as calcite, wollastonite, phlogopite, plagioclase, diopside and others.There are few quarries of lapis lazuli in the world, and only some of them could be used since 7000 years ago. In particular the Afghan mines in the Badakhshan region have been considered for long time as the only source of lapis lazuli already exploited to provide the raw material to ancient civilization of Mesopotamia, Egypt, Indus Valley and China. In more recent times also other sources have been taken in consideration: Pamir mountains (Lyadzhuar Dara, Tajikistan), Pakistan (Chagai Hills), Siberia (Irkutsk, near Lake Baikal) and others not yet geologically confirmed. Despite the knowledge of the provenances of the raw material can help reconstructing trade routes of the past, a systematic and exhaustive provenance study of the raw material utilized in artworks is still lacking. For this reason we started a multi-technique characterization of twelve samples of certain provenance (Afghanistan, Pamir, Siberia and Chile), coming from the collection of the Mineralogy and Lithology section of the Museum of Natural History, University of Firenze. The final aim of the work is to find some markers to distinguish among the analysed provenances and to use them to identify the origin of the raw material used for artworks and archaeological findings. The samples were prepared as semi-thin sections and have already been analysed both with electron-beam (SEM-EDX, SEM-CL, cold-cathodoluminescence) and ion-beam techniques (PIXE, IL), to study both the elemental composition of the phases and their luminescence response. To complete the characterization of the material and to recognize the various phases present inside the samples of different provenances we performed a systematic study by means of micro-Raman spectroscopy. We already demonstrated that luminescence spectra can give useful information for the provenance discrimination of the analysed provenance and in this work we’ll explore the possibility to find some new markers studying the minor peaks of the Raman spectra of the different phases inside lapis lazuli.
Characterization of lapis lazuli from different provenances by means of micro-Raman spectroscopy
ANGELICI, Debora;LO GIUDICE, Alessandro;RE, ALESSANDRO
2011-01-01
Abstract
Lapis lazuli is a blue semi-precious stone widely used since the antiquity for the manufacture of precious objects and jewellery. It’s characterized by the presence of the mineral lazurite, giving the typical blue colour to the rock, traversed by gray-white or yellowish veins, due to the presence of various accessory minerals such as calcite, wollastonite, phlogopite, plagioclase, diopside and others.There are few quarries of lapis lazuli in the world, and only some of them could be used since 7000 years ago. In particular the Afghan mines in the Badakhshan region have been considered for long time as the only source of lapis lazuli already exploited to provide the raw material to ancient civilization of Mesopotamia, Egypt, Indus Valley and China. In more recent times also other sources have been taken in consideration: Pamir mountains (Lyadzhuar Dara, Tajikistan), Pakistan (Chagai Hills), Siberia (Irkutsk, near Lake Baikal) and others not yet geologically confirmed. Despite the knowledge of the provenances of the raw material can help reconstructing trade routes of the past, a systematic and exhaustive provenance study of the raw material utilized in artworks is still lacking. For this reason we started a multi-technique characterization of twelve samples of certain provenance (Afghanistan, Pamir, Siberia and Chile), coming from the collection of the Mineralogy and Lithology section of the Museum of Natural History, University of Firenze. The final aim of the work is to find some markers to distinguish among the analysed provenances and to use them to identify the origin of the raw material used for artworks and archaeological findings. The samples were prepared as semi-thin sections and have already been analysed both with electron-beam (SEM-EDX, SEM-CL, cold-cathodoluminescence) and ion-beam techniques (PIXE, IL), to study both the elemental composition of the phases and their luminescence response. To complete the characterization of the material and to recognize the various phases present inside the samples of different provenances we performed a systematic study by means of micro-Raman spectroscopy. We already demonstrated that luminescence spectra can give useful information for the provenance discrimination of the analysed provenance and in this work we’ll explore the possibility to find some new markers studying the minor peaks of the Raman spectra of the different phases inside lapis lazuli.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
