What is "tetrafluoroberyllate"

n. (context inorganic chemistry English) The anion BeF₄^2- or any salt containing this anion

Tetrafluoroberyllate or orthofluoroberyllate BeF is an anion containing beryllium and fluorine. The ion has a tetrahedral shape, the same size and outer electron structure as sulfate. Therefore, many compounds that contain sulfate, have equivalents with tetrafluoroberyllate. Examples of these are the Langbeinites, and Tutton's salts.