Microscopic scale characterization of ancient building sandstones from Saxony (Germany)

Sandstone has been a traditional building material all over the world for centuries and is still used for this purpose today. Because of the various geological origin, sandstones may differ in petrography and mineralogy, which mainly determine their technical properties and weathering behavior. Therefore, a careful investigation of sandstone building materials is required and a complex analytical scheme was developed for this purpose. Sample material from important quarry regions of the Elbe Zone (Saxony, Germany) was investigated, which supplied material for a lot of famous buildings in the historic city center of Dresden, in Meissen and in the whole state of Saxony. The complex study included macroscopic rock description and detailed investigations by polarizing microscopy (phase composition, texture, grain size distribution), cathodoluminescence (CL) microscopy (quartz types, feldspar and kaolinite content), scanning electron microscopy (SEM; accessories, pore cement, diagenetic grain surface features), and pore-size distribution by Hg porosimetry. In a case study, mineralogical and technical properties of building sandstones from the Meissen cathedral (Saxony, Germany) were investigated and compared with material from potential historical source quarries. The results of the present study allowed to assign unequivocally historically used material to specific sandstone occurrences, and provide a comprehensive basis for the interpretation of weathering damage on the historical monuments. These data are useful for current conservation and reconstruction activities