Noah Webster
Eurite
EU'RITE, noun The white stone [weiss stein] of Werner; a very small-grained granite, with the parts intimately blended, and hence often apparently compact. It is gray, red, etc., according to the color of the felspar, of which it is principally composed.
Whitestone is a finely granular felspar, containing grains of quartz and scales of mica.