Tin bent, a crackling sound known as the "tin cry" can be heard from the twinning of the crystals. Tin melts at low temperatures of about , the lowest in group 14. The melting point is further lowered to for 11 nm particles. β-tin (the metallic form, or white tin, BCT structure), which is stable at and above room temperature, is malleable. In contrast, α-tin (nonmetallic form, or gray tin), which is stable below , is brittle. α-tin has a diamond cubic crystal structure, similar to diamond, silicon or germanium. α-tin has no metallic properties at all because its atoms form
Wedding customs by country were considered a personal event and inviting people to the wedding who are not known to at least one member of the couple well enough to be able to choose an appropriate gift was considered inappropriate, and registries should therefore be unnecessary. Whether considered appropriate or not, others believe that weddings are opportunities to extract funds or specific gifts from as many people as possible, and that even an invitation carries an expectation of monetary reward rather than merely congratulations. Letters of thanks for any gift are traditionally sent promptly after the gift's receipt. Tradition allows wedding gifts to be