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 anniversary can receive a message from the monarch for 60th, 65th, and 70th wedding anniversaries, and any wedding anniversary after that. This is done by applying to Buckingham Palace in the United Kingdom, or to the Governor-General's office in the other Commonwealth realms. In Australia, where one can receive a letter of congratulations from the Governor-General on the 50th and all subsequent wedding anniversaries; the Prime Minister, the federal Opposition leader, local members of both state and federal parliaments, and state Governors may also send salutations for the same anniversaries. In Canada, one can also receive a message from the Governor-General