The Leonorenquelle in Bad Salzig is a mineral spring, a mineral bath and an acidulous water.

The beginnings of the mineral spring go back to Roman times. Salt wells are mentioned several times in the 18th and 19th centuries. In 1840 there were first efforts to use the mineral springs. It was then used from 1902-1905 on behalf of Hauptmann i. R. Theodor Hoffmann, after he bought the source area in 1889. The 28° warm healing water of the carbonated, alkaline-muratic Glauber's salt spring bubbles up from a depth of almost 500m.

According to the current "Definitions for health resorts, resorts and healing fountains" of the German Baths Association and the German Tourist Association, the water of the "Leonorenquelle" in Bad Salzig is to be labeled as "sodium chloride hydrogen carbonate sulphate water".

It is said that the water from mineral springs bears the signature of the rock over which it has flowed. In an aqueous solution, they contain those substances that can be extracted from the stone and are therefore a reflection of geology and time.

The rock minerals determine the components of the solvent water, and the contact time is decisive for the concentration. Based on the composition of dissolved minerals, conclusions can be drawn about the rocks in the subsoil and how long the water must have been in contact with them. Furthermore, one can draw conclusions about how the rocks were formed.