Patent attributes
Provided are: a spherical magnesium oxide having not only high sphericity but also smooth surface and having excellent moisture resistance and excellent filling properties, and a method producing the same. In the present invention, by controlling the boron and iron contents of the calcined magnesium oxide to be in the respective predetermined ranges, there is provided a spherical magnesium oxide having a volume-based cumulative 50% particle diameter (D50), as measured by a laser diffraction/scattering particle size distribution measurement, in the range of from 3 to 200 μm, which is the range for a relatively large particle diameter, and a high sphericity of 1.00 to 1.20, as measured from viewing a SEM photomicrograph, as well as smooth surface, and having excellent moisture resistance and excellent filling properties. A predetermined spherical magnesium oxide is provided by virtue of the synergies obtained from the boron content of 300 to 2,000 ppm and the iron content of 100 to 1,500 ppm.
