Caltanissetta, which occupies the middle point in elevation as well as in respect of geographical situation, stands 1900 ft.
The archiepiscopal sees (the suffragan sees, if any, being placed after each in brackets) are Catania (Acireale), Messina (Lipari, Nicosia, Patti), Monreale (Caltanissetta, Girgenti), Palermo (Cefalu, Mazara, Trapani), Syracuse (Caltagirone, Noto, Piazza Armerina).
The most important Sicilian mineral is undoubtedly sulphur, which is mined principally in the provinces of Caltanissetta and Girgenti, and in minor quantities in those of Palermo and Catania.