Silica sandstone
Quarry Cotta near Pirna
Quarzsandstein
Silica sandstone
The shell imprints in this sandstone prove its formation in a calm shelf sea and the complete dissolution of the shells after the sandstone solidified. It is almost 100% quartz grains, but also contains clayey substance that creates a characteristic fibrous structure. These are the linings of burrows created by small crabs.
Labiatus sandstone (sculptural sandstone), Schmilka Formation, Turonian, Cretaceous; Cotta Quarry near Pirna, Elbe Sandstone Mountains, c. 93 Ma
Location: Quarry Cotta near Pirna
Age: ca. 93 million years
Cotta bei Pirna
Quartz sandstone from Cotta is a rock of great geological importance and is also called Cotta sandstone or central ashlar. It is found in the Elbe Valley as well as in numerous side valleys and is mainly found in the western part of the Elbe Sandstone Mountains, which extend to the Bohemian border. The Cotta sandstone received its name due to its occurrence in the region around Cotta, a district of Dohma, which is located near the quarry.
The quartz sandstone was formed in the Cretaceous period, more precisely in the lower Turonian. It exhibits a variety of colors, including whitish, grayish, grayish-yellowish, and brownish. The grain size varies depending on the geographic location. In the south, the sandstone is medium-grained, while in the north it is fine-grained. Near Cotta, the grains are uniform in size, usually between 0.1 and 0.22 millimeters, rarely up to 0.3 millimeters. The rock contains small amounts of mica minerals (glauconite), clay and coal particles. The coal is deposited in clearly visible veins and sometimes gives the stone a marbled texture.
The technical properties of this natural stone vary greatly, as quartz sandstone can have different quartz grain contents. It has a high compressive strength and is therefore well suited for use in the construction industry. Due to its aesthetic qualities, quartz sandstone is often used for sculptures, facade cladding and architectural elements.
The Cotta quarry near Pirna provides an important source of quartz sandstone. The region around Cotta is scenic and lies on the western edge of Saxon Switzerland, which is part of the Elbe Sandstone Mountains. The Cottaer Spitzberg, a prominent basalt rock, rises directly south of the village and is protected as a natural landmark. The top of the Cottaer Spitzberg is more than 70 meters above the village and offers an impressive panoramic view.
Location of the rock quartz sandstone from the quarry Cotta near Pirna