When I was a kid, I use to look for small rocks which were different than usual ones, shiny and mysterious. I knew a few spots around where I can find it. Today I know it was calcite mineral, very common in Bosnia.
Last year I was on a fair of crystals in Kreševo, a small town near Sarajevo, with great people and interesting findings on surrounding hills. This area is known for different kind of crystals and beautiful minerals from ancient times, even before old Romans.