Two large masses, one ring-shaped (the Signet or Irwin-Ainsa Iron) of 688kg and the other (the Carleton Iron) of 287kg known for centuries, had been transported to Tucson from the Puerta de los Muchacos, a pass 20-30 miles S of that town and were used as anvils; first mentioned by J.F.Velasco in 1850, M.H.Hey, Cat. Met., 1966, p.491. Bibliography, with analyses, L.Fletcher, Min. Mag., 1890, 9, p.16. Bibliography for the period 1850-1876, P.J.McGough, Pop. Astron., Northfield, Minnesota, 1943, 51, p.511, 564, and 1944, 52, p.243. Detailed history, with bibliography, R.R.Willey, The Tucson Meteorites, Washington D.C., 1986, 56 pp. A unique iron with silicate inclusions, containing brezinaite, (Cr3S4), T.E.Bunch and L.H.Fuchs, Amer. Miner., 1969, 54, p.1509. Analysis, 9.45% Ni, 0.94 ppm Ga, 0.049 ppm Ge, 2.1 ppm Ir, orthopyroxene Fs0.4 in silicate inclusions, J.T.Wasson, GCA, 1970, 34, p.957. The Carleton mass has been heated and forged; different coordinates, weights of masses, V.F.Buchwald, Handbook of Iron Meteorites, Univ. of California, 1975, p.1235. Further chemical analysis, 9.82% Ni, 0.54% Co, M.I.Dyakonova and V.Y.Kharitonova, Meteoritika, 1975, 34, p.65. Microstructure and cooling rate calculation, the meteorite was rapidly cooled, G.T.Miyake and J.I.Goldstein, GCA, 1974, 38, p.1201. Further analysis, E.R.D.Scott, GCA, 1978, 42, p.1243. Relationship to enstatite meteorites; mineralogy and chemical composition of silicate inclusions, C.E.Nehru et al., J. Geophys. Res., 1982, 87, (suppl.), p.A365. Further analysis data of metallic and non-metallic phase, H.W.