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 ring Romania, spouses celebrate their silver wedding anniversary, i. e., twenty-fifth anniversary, by exchanging silver wedding rings, which are worn on the fourth finger of the left hands along with their original, and usually gold, wedding rings. While most Christian Churches (such as the Catholic, Lutheran, and Anglican) have the exchange of rings within their wedding liturgies, some Christian denominations eschew the use of wedding rings. The wearing of plain dress has historically been practiced by many Methodist Churches, in keeping with the teaching of John Wesley, who stated that people should not be "adorned with gold, or pearls, or costly