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    Allotropes are various modifications of the same element that differ in the atomic lattice structure or the bonding behavior. These will mostly transform into each other at a certain temperature. Tin is used for example as α -tin (gray tin) with a cubic crystal lattice and as β -tin (white tin) with a tetragonal crystal lattice. The latter is the metallic tin with a glossy finish, commonly used in soldering, but transformed at -30°C Storage temperature into α -tin. Arsenic also has three different allotropes with three different colors: gray, yellow and black. The gray arsenic is the ordinary metallic form with a hexagonal crystal system while the yellow arsenic is a cubic crystal. The latter is transformed into gray arsenic by simple exposure to light. Iron occurs as α -Fe (ferrite) with a cubic body-centered lattice and as γ -Fe (austenite) with a face-centered cubic lattice. See also Tin pest.