Chemical Composition: ICP-MS/AAA data from sample, Bronze:
Cu, 89.92; Sn, 9.38; Pb, 0.21; Zn, 0.045; Fe, 0.07; Ni, 0.02; Ag, 0.07; Sb, 0.11; As, 0.17; Bi, less than 0.025; Co, less than 0.005; Au, less than 0.01; Cd, less than 0.001
J. Riederer
Chemical Composition: XRF data from Tracer
Alloy: Bronze
Alloying Elements: copper, tin
Other Elements: lead, iron, silver, antimony, arsenic
K. Eremin, January 2014
Chemical Composition: EMP analysis from sample, Bronze:
Cu, 89.45; Sn, 8.86; Pb, 0.11; Zn, 0.00; Fe, 0.08; Ni, 0.00; Ag, 0.05; Sb, 0.16; As, 0.04
M. McNamara, October 2000
Technical Observations:
This helmet is incomplete; the lower sections on the back of the proper right side and the proper right cheek guard are lost. The intact cheek guard has been bent backward and subsequently straightened. X-radiographs reveal a fracture in the dome on the proper right and a weakness in the metal where the cheek guard was bent backward. The patina is dark green to gray with intermittent spots of emerald green and red-brown corrosion. The surface is covered with shallow and deep corrosion-filled pits.
Helmets 1916.362 and 1956.18 are each made from a single piece of metal. X-radiographs reveal a mottled appearance that corresponds to small, round hammer marks applied in a concentric pattern around the crowns. An x-radiograph of the cheek guard on 1916.362 shows stacked rows of hammer marks running across the guard at a slight (c. 35 degree) angle. There is no evidence of gates, risers, chaplets, or porosity from casting on either helmet.
Metallographic examination of 1916.362 reveals intergranular corrosion, which confirms that the metal is ancient. Deformation lines, along with both straight and bent annealing twins visible in the etched microstructure, indicate numerous cycles of hammering and annealing. There is no clear evidence of how the egg-and-dart pattern was made, but etched sections show that the linear decoration beneath the egg-and-dart was made by cutting, rather than punching or casting. There is no evidence of coring, a dendritic structure, or porosity, which are all microstructural features consistent with casting. 1956.18 was not sampled for metallography or elemental analysis.
Molly McNamara (submitted 2000)