1851 H. Watts tr. L. Gmelin V. 212 Mottled or mixed pig-iron.
1858 7 May 384/2 1/ 3 white iron and 2/ 3 mottled pig.
a1898 H. Bessemer (1905) xviii. 275 The analysis of mottled pig (la fonte truité), consisting of two-thirds gray and one-third white.