Analyses of Mortars from St. George’s Cathedral, Great Novgorod

The Yuriev Monastery at Veliky Novgorod - one of the oldest monasteries in Russia – was founded in the 12th century by Prince Vsevolod Mstislavich. Now it is a UNESCO World Heritage Site. The dominating building of the Monastery is the Cathedral of St. George. It was constructed in 1119 and painted before 1130. During the archaeological research of 2021 carried out by the Department of Archaeology and Architecture of the Institute of Archaeology, Russian Academy of Sciences (Moscow), 15 samples of lime-mortar from the Cathedral and 2 more from an unknown building in the Monastery area were collected. Microscopy of cross sections and polarized transmitted light microscopy of thin sections were carried out to investigate the main components and differences in the mortars. Based on these analyses, the differences between mortars used in the various structural elements of the first (pre-Mongolian) building period and of the later periods were observed. The presences of crushed bricks (tsemyanka) – the main component of pre-Mongolian mortars – was found in the later mortars. Distinctions between different kinds of mortars (wall mortar, foundation mortar, floor mortar) and plaster were defined. Two types of sand used in the medieval mortars were identified. The preliminary dating of unknown construction found during the archaeological excavation by late 12th or 14th century was made.