Redfern S A T , Harrison R J , O Neill H St C , Wood D R R , American Mineralogist , 84 (1999) p.299-310, Thermodynamics and kinetics of cation ordering in MgAl2O4 spinel up to 1600 C, from in situ neutron diffraction, Data collected at IPNS, Argonne National Laboratory,, T = 1299 K on cooling cycle, Mg.99Al2O4