{"id":47674,"date":"2020-06-10T17:53:02","date_gmt":"2020-06-10T15:53:02","guid":{"rendered":"http:\/\/www.icac.cat\/en\/?p=47674"},"modified":"2020-06-11T08:51:42","modified_gmt":"2020-06-11T06:51:42","slug":"the-light-on-marble-a-new-analytic-tool-to-identify-the-great-classic-marbles","status":"publish","type":"post","link":"https:\/\/icac.cat\/en\/actualitat\/noticies\/2020\/the-light-on-marble-a-new-analytic-tool-to-identify-the-great-classic-marbles\/","title":{"rendered":"The light on marble: a new analytic tool to identify the great classic marbles"},"content":{"rendered":"

A new\u00a0paper published in the journal Minerals<\/em> <\/strong><\/a>presents the advances in the application of cathodoluminescence (CL) in the study and identification of white marbles used in the classical era.<\/p>\n

The\u00a0cathodoluminescence\u00a0<\/strong>(CL) is an optical and electromagnetic phenomenon which occurs when an electron beam bombards matter, producing the emission of visible light.\u00a0That is, emitting a luminescence.<\/p>\n

This light varies depending on the chemical composition.\u00a0In geology, it is often applied in combination with the petrographic microscope not only to distinguish between minerals but also to examine the internal structures of rocks, a key element in explaining the history of their formation.<\/p>\n

With this new work, a step forward is made in the use of this technique and in the distinction between the different\u00a0white marbles\u00a0<\/strong>used in the Greco-Roman world.\u00a0These materials are among the quintessential noble materials of the classical antiquity.\u00a0It is not by chance that they were profusely used to make sculptures, sarcophagi, furniture, epigraphic inscriptions… as well as in the decoration of large monumental buildings or of villas and residences of social elites.<\/p>\n

Paper authors are\u00a0Ph<\/strong>.\u00a0<\/strong>Blanc<\/strong><\/a>\u00a0(emeritus professor at the Pierre and Marie Curie University – La Sorbonne),\u00a0Pilar Lapuente<\/strong><\/a>\u00a0(University of Zaragoza –\u00a0ICAC associate researcher\u00a0) and\u00a0Anna Guti\u00e9rrez\u00a0<\/strong>Garcia<\/strong>-M.<\/strong><\/a>, head of the\u00a0Archeometric\u00a0Studies\u00a0Unit<\/a>\u00a0(UEA) at the ICAC.<\/p>\n

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This new paper\u00a0presents two major milestones. On one side, one of the main limitations of optical CL is overcome, thanks to the quantification of the spectra and intensities of the luminescent response and the\u00a0development of a specific methodology<\/strong>. On the other side, the\u00a0first CL-quantitative database<\/strong>,\u00a0<\/strong>resulting from the application of this technique, is now available to the scientific community.<\/p>\n<\/div>\n

The new method consists of preparing samples of the marble powder, and then place them on a plate specifically designed to be pressed and introduced into the scanning electron microscope (SEM) with an attached spectrometer.\u00a0Thus, the specific spectra and the intensity of these spectra can be obtained for each of the samples.<\/p>\n

\"Seq\u00fc\u00e8ncia
Sample preparation sequence for CL-quantitative analysis developed by Ph. Blanc at UPMC, Paris (\u00a9 Ph. Blanc)<\/figcaption><\/figure>\n

Given the intrinsic instability of light emissions, numerous tests have been carried out under different experimental conditions, to obtain the greatest number of responses and to calibrate the protocol to obtain representative results.<\/p>\n

Furthermore, this technique has been applied to a set of\u00a0c.\u00a0<\/em>500 samples of marbles\u00a0<\/strong>from Italy (quarries of Carrara), Asia Minor (quarries of\u00a0G\u00f6ktepe,\u00a0Afyon\u00a0and\u00a0Afrodisies) and Greece (quarries of the Pentelico, Tassos, Naxos, Paros and\u00a0Proconeso) with extremely interesting results (especially once related to optical CL parameters) that confirm the great potential of quantitative CL as a complementary tool to current analyzes and with which to distinguish not only between the different white marbles but also between different quarries in the same extraction area.<\/p>\n

\"Diferents
Different experimental tests on a marble sample (G13) obtained in the Carrara quarries (\u00a9 ICAC)<\/figcaption><\/figure>\n

This study is the continuation of a line of research initiated at the time by\u00a0Ph.\u00a0Blanc<\/strong>, one of the pioneers in the application of cathodoluminescence (CL) to the analysis of ancient marble. The technique was adopted by the ICAC’s Archaeometric\u00a0Studies Unit, from a decade ago, as an\u00a0essential part of the analytical protocol, thanks to the collaboration with\u00a0Pilar Lapuente<\/a><\/strong>.<\/p>\n

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Thus, the\u00a0UEA<\/a>\u00a0has become one of the world reference laboratories in this technique.\u00a0Currently, the Unit team is working to include peninsular and Pyrenean marbles in this reference database, with the expectation of obtaining positive results in the short term.<\/p>\n<\/div>\n

 <\/p>\n

Research results published in\u00a0Minerals<\/em><\/strong><\/a>\u00a0come from the research lines developed by\u00a0ArPA\u00a0<\/strong>research\u00a0team<\/a>\u00a0(Archeometry\u00a0<\/strong>and Artistic Productions)\u00a0and, specifically, the following research projects:<\/p>\n