Mt, Une; at. no. 109. Group VIII( 9). No stable nuclides. Prepn of isotope 266109 (T 1/2 ≈3.5 msec, α-decay) by 209Bi(58Fe,n): G. Münzenberg et al., Z. Phys. A309, 89 (1982); eidem, ibid. A315, 145 (1984). Review of synthesis: G. N. Flerov, G. M. Ter-Akopian, Prog. Particle Nucl. Phys. 19, 197-239 (1987); G. T. Seaborg in Transuranium Elements: A Half Century, L. R. Morss, J. Fuger, Eds. (Am. Chem. Soc., Washington DC, 1992) p 41-42.