Non-metallic inclusions, the presence of which defines purity of steel, are classified by chemical and mineralogical content, by stability and by origin.
nˈɑːnmətˈælɪk ɪŋklˈuːʒənz, ðə pɹˈɛzəns ʌvwˈɪtʃ dᵻfˈaɪnz pjˈʊɹɹᵻɾi ʌv stˈiːl, ɑːɹ klˈæsᵻfˌaɪd baɪ kˈɛmɪkəl ænd mˌɪnɚɹɐlˈɑːdʒɪkəl kˈɑːntɛnt, baɪ stəbˈɪlᵻɾi ænd baɪ ˈɔːɹɪdʒˌɪn.