hˈiːɾɪŋ ɹˌiː tˈuː ˈoʊ sˈɛvən ɡˈɪvz ɹˈiːniəm daɪˈɑːksaɪd, ɐ ɹɪˈækʃən sˈɪɡnəld baɪ ðɪ ɐpˈɪɹəns ʌvðə dˈɑːɹk blˈuː kˌʌlɚɹˈeɪʃən:
Heating Re2O7 gives rhenium dioxide, a reaction signalled by the appearance of the dark blue coloration: