Any mineral belonging to the feldspathoid group.

Group of minerals that are very similar to the feldspars. The difference is that the feldspathoids lacked the amount of silica to fully make them into feldspars when they were formed. They, as feldspars, are aluminum silicates of potassium, sodium, and/or calcium. The feldspathoid group is in the tectosilicates subdivision of the silicates group.

any of a group of rock-forming minerals chemically similar to the feldspars but containing less silica. [AHDOS