ɪɾ ɪz kəmpˈoʊzd mˈoʊstli ʌv ˈaɪɚn θˈɜːɾi tˈuː.wˈʌn pɚsˈɛnt, ˈɑːksɪdʒən θˈɜːɾi.wˈʌn pɚsˈɛnt, sˈɪlɪkən fˈɪftiːn.wˈʌn pɚsˈɛnt, mæɡnˈiːziəm θˈɜːtiːn.nˈaɪn pɚsˈɛnt, sˈʌlfɜː tˈuː.nˈaɪn pɚsˈɛnt, nˈɪkəl wˈʌn.ˈeɪt pɚsˈɛnt, kˈælsiəm wˈʌn.fˈaɪv pɚsˈɛnt, ænd ˌæljʊmˈɪniəm wˈʌn.fˈoːɹ pɚsˈɛnt; wɪððə ɹᵻmˈeɪnɪŋ wˈʌn.tˈuː pɚsˈɛnt kənsˈɪstɪŋ ʌv tɹˈeɪs ɐmˈaʊnts ʌv ˈʌðɚɹ ˈɛlɪmənts.
It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminium (1.4%); with the remaining 1.2% consisting of trace amounts of other elements.