Fluorine
Fluorine is a faintly colored greenish-yellow gas with a sharp odor; its inhalation is hazardous since it irritates mucous membranes and causes corrosion. It is stored under pressure in steel containers; it is a highly reactive element that ignites organic materials, particularly wood, fats, and textile materials.
Fluorine is used for the preparation of certain fluorides and fluorinated organic derivatives
Source: "Explanations to the Customs Tariff of Foreign Economic Activity of the Russian Federation (HS of Russia)" (prepared by the Russian Federal Customs Service) (Volume 1, Sections I - VI, Groups 1 - 29)