Crystal structure "white tin" respectively. Two more allotropes, γ and σ, exist at temperatures above 161 °C and pressures above several GPa. White tin is metallic, and is the stable crystalline form at or above room temperature. Below 13.2 °C, tin exists in the gray form, which has a diamond cubic crystal structure, similar to diamond, silicon or germanium. Gray tin has no metallic properties at all, is a dull gray powdery material, and has few uses, other than a few specialized semiconductor applications. Although the α–β transformation temperature of tin is nominally 13.2 °C, impurities (e.g. Al, Zn, etc.) lower the
Wedding ducks Wedding ducks Wedding ducks () are a pair of duck carvings (traditionally Mandarin ducks) that are used in Korean wedding ceremonies, and often given as marriage gifts. Mandarin ducks are chosen because it is believed that, unlike other types of ducks, they mate for life, and that if one of the pair dies, the other will mourn. For Koreans, Mandarin ducks represent peace, fidelity, and plentiful offspring. Originally, a man who wished to marry would purchase pairs of live ducks or geese to give as a gift to the family of the prospective bride. That tradition gave way to using