Correct spelling for the English word "isopyre" is [ˈa͡ɪsəpˌa͡ɪ͡ə], [ˈaɪsəpˌaɪə], [ˈaɪ_s_ə_p_ˌaɪə] (IPA phonetic alphabet).
A mineral of a greyish or black colour and of vitreous lustre.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.