Tin pest related problems such as tin whiskers. At 13.2 °C (about 56 °F) and below, pure tin transforms from the silvery, ductile metallic allotrope of β-form "white tin" to the brittle, nonmetallic, α-form "grey tin" with a diamond cubic structure. The transformation is slow to initiate due to a high activation energy but the presence of germanium (or crystal structures of similar form and size) or very low temperatures of roughly −30 °C aids the initiation. There is also a large volume increase of about 27% associated with the phase change to the nonmetallic low temperature allotrope. This frequently makes tin
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