Feldspath

Etymology

The name feldspar derives from the GermanFeldspat, a compound of the words Feld ("field") and Spat ("flake"). Spat had long been used as the word for "a rock easily cleaved into flakes"; Feldspat was introduced in the 18th century as a more specific term, referring perhaps to its common occurrence in rocks found in fields (Urban Brückmann, 1783) or to its occurrence as "fields" within granite and other minerals (René-Just Haüy, 1804). The change from Spat to -spar was influenced by the English word spar, meaning a non-opaque mineral with good cleavage. Feldspathic refers to materials that contain feldspar. The alternative spelling, felspar, has fallen out of use. The term "felsic", meaning light coloured minerals such as quartz and feldspars, is an acronymic word derived from feldspar and silica, unrelated to the obsolete spelling "felspar".