Iron, covered with a thin silver sheet bound at the edges with a copper sheet U-channel.
Between the iron and silver layers, there was a layer of glued-on material (felt?).
It is debatable as to whether this is a cavalry mask, or an infantry signifer's mask (or some other standard bearer).
References:
Franzius, G., (1995), "Die Römische Funde aus Kalkriese, 1987-95", J.R.M.E.S., 6, 69-88, Abb.3
Franzius, G., (1991), "Die Maske eine Geschichteshelmes" in Schlüter, W., (1991), "Die Römer in Osnabrücker Land. Die Archäologischen Untersuchungen in der Kalkriese-Niewedder Senke", 53ff.
Hanel, N., Peltz, U. & F. Willer, (2000); 'Untersuchungen zu römischen Reiterhelmmasken aus der Germania inferior'. Bonner Jahrbücher, 200, 272
Hanel, N., Wilbers-Rost, S & Willer, F. (2004), "Die Helmmaske von Kalkriese", Bonner Jahrbücher, 204, 71-92
