The hexagonal form, which is closely related to the monoclinic form, containing Ga24+ units,  converts to the monoclinic form when annealed at 500 °C.
ðə hˈɛksɐɡənəl fˈɔːɹm, wˌɪtʃ ɪz klˈoʊsli ɹᵻlˈeɪɾᵻd tə ðə mˌɑːnoʊklˈɪnɪk fˈɔːɹm, kəntˈeɪnɪŋ ɡˈɑː twˈɛnti fˈoːɹ plˈʌs jˈuːnɪts,  kənvˈɜːts tə ðə mˌɑːnoʊklˈɪnɪk fˈɔːɹm wɛn ɐnˈiːld æt fˈaɪvhˈʌndɹɪd dᵻɡɹˈiːz sˈiː.