Vitreous forsterite (Mg 2 SiO 4 ): Synthesis, structure, and thermochemistry

Here we report the first synthesis of a forsterite (Mg 2 SiO 4 ) composition glass as an essentially phase‐pure bulk material. Under containerless conditions, with heterogeneous nucleation sites minimized, glass forms by cooling ca. 1 mm liquid Mg 2 SiO 4 droplets in oxygen at 700 K/s. 29 Si NMR spectroscopic data indicate that the SiO 4 tetrahedra and MgO 6 octahedra exist in a corner sharing arrangement in the glass, but upon crystallization the polyhedral units reorganize to form edge‐sharing linkages. Transposed temperature drop calorimetry shows that the glass is 61.4±1.3 kJ/mol higher in enthalpy than the crystal.