FIELD: metallurgy, more particularly composition for modifying gray cast iron. SUBSTANCE: composition comprises, wt.%: rare-each elements, 1.0-4.0; strontium, 0.5-1.5; calcium, not more than 1.5; aluminium, not more than 2.0; silicon; 40.0-80.0; and the iron balance, ratios of components being as follows, wt.%: rare-earth elements, 1.5-2.5; strontium, 0.7-1.0; calcium, not more than 0.5; aluminium, not more than 0.5; silicon, 70.0-75.0; and the iron balance. The claimed variants of compositions for modifying gray cast iron reduce discoloration rate of cast iron, make it possible to produce gray cast iron having structure containing random distribution of graphite flaxes of identical size. EFFECT: improved properties of the composition. 7 cl, 3 ex, 2 tbl
