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Salt crystallisation is a principal deterioration factor of many stone monuments. In this study, samples of weathering products of two baroque monuments in Ljubljana, Slovenia (the Fountain of Three Carniolian Rivers and the side altar of the Church of St. James), as well as the limestone used in their construction (Lesno Brdo limestone) were investigated in order to ascertain the main mineral phases produced during the weathering process. A combination of micro-Raman spectroscopy and X-ray powder diffraction was successfully applied to identify micrometre-size minor components in the limestone and the weathering product phases. In addition to calcite and dolomite as the main components of the Lesno Brdo limestone, quartz, anatase, goethite, haematite and phyllosilicates were also determined as minor limestone minerals. The limestone was found to be extensively deteriorated in both outdoor and indoor environments in the studied historical monuments, showing flaking, subflorescence, efflorescences, crumbling and black and white crusts as a result of the deterioration phenomena. Among these weathering forms, efflorescences were found to be more complex in terms of mineral assemblage, where gypsum was associated to hexahydrite, pentahydrite, and nitre. In contrast to the efflorescences, the mineralogy of subflorescences as well as that of white and black crust from outdoor and indoor conditions was rather simple, composed of only gypsum. The results showed that gypsum also crystallised under the surface as subflorescence, which eventually led to the flaking and crumbling of the limestone.

The study deals with the characterization of pigments from the newly discovered wall painting at the Dominican Monastery in Ptuj (Slovenia) in order to acquire detailed information about the technology used, as well as to identify the deterioration products. The uncovered wall painting, depicting a vivid procession of riders, is dated to the late 14th century. Painting techniques and pigments were analysed by optical microscopy and Raman microspectroscopy. The optical microscope revealed that the wall painting was executed in a lime technique characteristic of the Central‐European artistic expression. Several natural and synthetic inorganic pigments, such as azurite, red and yellow ochres, cinnabar, red lead, lead white, lime white, lead–tin yellow type I and carbon black were identified. Surprising identification of the type I of lead–tin yellow used already in the 14th century is of high importance, since, until now, it was considered that it appeared on the market only in the first half of the 15th century. Plattnerite was observed as a result of degradation of lead pigments. The use of expensive azurite and cinnabar could indicate a wealthy client. Copyright © 2014 John Wiley & Sons, Ltd.

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