Historia zapisana w kamieniu romańskiej kolegiaty pw. św. Marcina w Opatowie

Romanesque collegiate church in Opatów (south-eastern Poland) belongs to the best-preserved Early Mediaeval edifices in Poland. Its date of origin, founder, architects and history are still unclear despite numerous investigations carried out since the beginning of the 19 th century. It is clear that local sandstones were used in the construction of the impressive church. Present investigations resulted in the inventory of the stones used as a building material: their petrography, size of blocks and strange holes and striae on some of their surfaces. Dominant sandstones have different colours: white-greyish or grey-brownish. They are built of very fine-grained, well sorted quartz with siliceous-clayey binder. All sandstone blocks have similar heights (most frequent average 34–38 cm), but different lengths. Longer (up to 62 cm) are placed in the oldest parts of the edifice, shorter (up to 48 cm) form younger fragments and might have been reused after destruction of previous undefined buildups. The sandstones represent Lower Jurassic sediments exposed currently on the slopes of the Opatówka River valley in Podole, some 5 km NE of Opatów. Only a few sherry (reddish) sandstone blocks found in various parts of the walls are probably replacements during post-Romanesque reconstructions. They represent Lower Triassic sandstone from Lipowa, 3 km NE of Opatów. Lancetoidal grooves, 5–20 cm long, and hemispherical holes of 1–4 cm in diameter are apparently of anthropogenic origin (apotropaic marks); however, their purpose is unclear. It is supposed that the grooves are traces of tool sharpening or grinding, while the holes are places where sandy or dusty material was acquired for magical or medical purposes.