A feldspathoid is a group of minerals that are similar to feldspar but contain little to no silica. They are typically found in volcanic rocks and are characterized by their low silica content, which distinguishes them from more common feldspar minerals. Feldspathoids can form in environments where silica is limited, leading to unique geological formations. Common types of feldspathoids include nepheline and sodalite. These minerals often occur in alkaline igneous rocks and can be important indicators of the geological conditions under which the rock formed. Feldspathoids are also used in various industrial applications, including ceramics and glass production.