Ubutare bw'icyuma bwo mu bishanga bwumishijwe — ni udukombe twa oksihidorokiside y'icyuma dukusanywa mu bishanga, mu mabwa no mu nsi y'imigezi. Ni bwo bwari isoko nkuru y'icyuma mu gushongesha kw'igihe cy'Abaviking, kubera ko bushonga ku bushyuhe buke kandi buboneka henshi mu Burayi bw'Amajyaruguru. Bugomba kumishwa no gucanwa mbere yo gushongeshwa kugira ngo hakurweho ubushuhe n'ibintu by'ibinyabuzima.