ðə kɹˈɪstɐlˌaɪn fˈɔːɹm ɛɡzˈɪsts ɪn tˈuː fˈeɪzᵻz, ðə kjˈuːbɪk bˈɪksbiˌaɪt tˈaɪp ænd ɹˌɑːmboʊhˈiːdɹəl kɔːɹˈʌndəm tˈaɪp.
The crystalline form exists in two phases, the cubic (bixbyite type) and rhombohedral (corundum type).