Pont--Mousson, Frouard, Lor Ardennes Charleville, Nouzon Sain-Bel (Rhne), manganese chiefly from Ariege and Sane-et.
Slate is obtained in large quantities from the departments of Maine-ct-Loire (Angers), Ardennes (Fumay) and Mayenne (Renaz).
Marne, united to the Ardennes on the north-eastern frontier by the wooded highlands of Argonne.
It is a long and narrow trough, which is separated from the older rocks of the Ardennes by a great reversed fault, the faille du midi.
In addition to being a forest the Ardennes is a plateau, and it offers to the geologist a most interesting field of investigation.
The Belgian Ardennes may be said now to extend from the Meuse above Dinant on the west to the grand duchy of Luxemburg and Rhenish Prussia as far north as the Baraque de Michel on the east, and from a line drawn eastward from Dinant through Marche, Durbuy and Stavelot to the Hautes Fagnes on the north, to the French frontier roughly marked by the Semois valley in the south.
The greater part of the Ardennes is occupied by a large area of Devonian beds, through which rise the Cambrian masses of Rocroi and Stavelot, and a few others of smaller size.
Copper is smelted in Ardennes and Pas-de-Calais.
In the Ardennes the system is represented by grits and sandstones, shales, slates and quartz schists, and includes also whet slates and some igneous rocks.