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
EMLL 15th Anniversary Show at Arena Modelo in 1933 and returned to that building in 1937 through 1943. From 1934 through 1936 EMLL rented Arena Nacional for their shows, but in 1944 they began holding their anniversary shows at Arena Coliseo, an arena they owned. From 1944 through 1955 EMLL held all their anniversary shows at Arena Coliseo. Traditionally EMLL/CMLL holds their major events on Friday Nights, replacing their regularly scheduled "Super Viernes" show. The event featured an undetermined number of professional wrestling matches with different wrestlers involved in pre-existing scripted feuds, plots and storylines. Wrestlers were portrayed as either heels (referred to as