As its name (salt in Slavonic) suggests, most of Slănic's history and economy are directly related to the presence of relatively large quantities of salt underground, and even in open air.
Slănic is also the name of the creek flowing through the town, tributary of Vărbilău River, which in turns is a tributary of Teleajen River.
Although technically incorrect, the compounded name Slănic Prahova is also being used especially in other parts of Romania. This alternative name was probably generated to help discern between Slănic and another Romanian town, Slănic Moldova.
http://en.wikipedia.org/wiki/Sl%C4%83nic