An Etymological Dictionary of the German Language/Spat

by Friedrich Kluge

Spat, m., ‘spar’ (mineral), from MidHG. spât, m., ‘foliated stone, splinter,’ whence Du. spaath, Fr. spath, and Ital. spato, ‘felspar,’ seem to be derived. Its origin is obscure, as in the case of Quarz.