Trace compounds in Early Medieval Egyptian blue carry information on provenance, manufacture, application, and ageing
Petra Dariz|Thomas Schmid
Abstract Only a few scientific evidences for the use of Egyptian blue in Early Medieval wall paintings Central and Southern Europe have been reported so far. The monochrome fragment discussed here belongs to second church building St. Peter above Gratsch (South Tyrol, Northern Italy, fifth/sixth century A.D.). Beyond cuprorivaite carbon black (underpainting), 26 accessory minerals down trace levels were detected by means Raman microspectroscopy, providing unprecedented insights into raw materials blend conversion reactions during preparation, application, ageing pigment. In conjunction with archaeological manufacture Cumae Liternum concordant statements antique Roman writers Vitruvius Pliny Elder, natural impurities quartz sand speak pigment produced at northern Phlegrean Fields (Campania, Italy). Chalcocite (and chalcopyrite) suggest sulphidic copper ore, water-insoluble salts mixed-alkaline flux form plant ash. Not fully reacted crystals partly intergrown only minimal traces silicate glass portend solid-state predominating chemical synthesis, while melting most likely played negligible role.
Scientific Reports|Library Union Catalog of Bavaria, Berlin and Brandenburg (B3Kat Repository)|PubMed Central|PubMed