A structure includes: a β silicon nitride crystal phase; and a Y2MgSi2O5N crystal phase. The structure gives a X-ray diffraction pattern by a θ-2θ method, the pattern having a ratio of a peak intensity of a (22-1) plane of the Y2MgSi2O5N crystal phase to a peak intensity of a (200) plane of the β silicon nitride crystal phase, the peak intensity of the (200) plane being determined at a position of 2θ=27.0±1°, the peak intensity of the (22-1) plane being determined at a position of 2θ=30.3±1°, and the ratio being 0.001 or more and 0.01 or less.