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.
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.