This site talks about naturally deformed feldspars. This site gives you an encyclopedias definition of feldspars and goes on to say what they are and where they can be found. They occur as single crystals or as masses of crystals and are the most abundant of all minerals and account for nearly half of the volume of the earth's crust. Feldspars can be found in granite, gneiss, basalt, and other crystalline rocks, and are in most igneous rocks. They create a large part of the clay found in our soils.
Pure feldspar is colorless and transparent but can be found in a variety of colors.
Orthoclase, which is the most common feldspar, and microcline are called potassium or potash feldspars. They usually are from flesh color to brick red, and are used in the making of porcelain and sometimes as a source of aluminum in making glass. A variety of microcline known as amazonite, or Amazon stone, is green and used for ornamental purposes. The plagioclase feldspars are occasionally red, but are usually gray. Another form of feldspar, labradorite, is used for decorative purposes, because it comes in an array of colors.