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1. A toxic nonmetallic element related to sulphur and tellurium; occurs in several allotropic forms; a stable grey metallike allotrope conducts electricity better in the light than in the dark and is used in photocells; occurs in sulphide ores (as pyrite)
   - Se, atomic number 34

Derived forms: seleniums

Type of: antioxidant, chemical element, element

Part of: fool's gold, iron pyrite, pyrite, selenite

Encyclopedia: Selenium