The underground rock salt mine Braunschweig-Lüneburg is the only productive mine in the Aller valley in Lower Saxony. Main topic of the visit will be the stratigraphy of the exposed Staßfurt to Aller formation as well as applied mining methods. The first shaft sinking activities started in 1910. In the beginning, the mine was built to produce potash from the “Kaliflöz Staßfurt”. Due to overproduction and decreasing potash contents in the mining horizon, the production ceased in 1922. From this time the mining activity changed to the production of a very pure rock salt from the salt bed “Kristallsalz” to be stratigraphically found in the Leine-Steinsalz. This layer is mainly steep bedded. Currently about 90 % of the rock salt production is delivered from the Lower Saxony part of the mine. According to the formation bedding the mining technique is preferably drilling and blasting. Further product processing as milling, sieving, optical sorting and packaging is performed in the adjacent factory on surface. The major portion (75 %) of the product with a purity of about 98.5 % NaCl is being processed for industrial purpose as alimentary and fishing industries. The excursion visits the mining chambers on the 490 m-level as well as the southeastern crosscut at the 390 m-level. At this point it is possible to encounter important parts of the stratigraphic cross section of the Staßfurt and Aller formation and allows closer insights into the lithological conditions of the rock salt. Additionally, the internal tectonic syn- and anticline structure characteristic for the eastern Allertal diapir can be observed.