β-tin, the metallic form or white tin, has BCT structure and is stable at and above room temperature and is malleable. α-tin, the nonmetallic form or gray tin, is stable below 13.2 C (55.8 F) and is brittle. α-tin has a diamond cubic crystal structure, similar to diamond, silicon or germanium. α-tin has no metallic properties, because its atoms form a covalent structure in which electrons cannot move freely. α-tin is a dull-gray powdery material with no common uses other than specialized semiconductor applications.[8] γ-tin and σ-tin exist at temperatures above 161 C (322 F) and pressures above several GPa.[11]
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