Tin selenide (tin selenide), MF SnSe, is a gray orthorhombic crystal, which is semiconducting. Density is 6.18 (g / ㎝³, 25/4 ° C), melting point is 861 ° C, insoluble in water, but soluble in nitric acid and aqua regia. The substance is highly toxic and harmful to the organic matter in water. In the conventional preparation method, the heating temperature must be higher than the melting point of the compound to reach 900 ~ 950 ° C to obtain high-purity SnSe.