Feldspar is the most common of all minerals. As you can see from the picture, feldspar has flat sides, or facets. When feldspar is broken into pieces, it often breaks with one or more flat sides. This is called "cleavage". Feldspar, quartz and mica are the most important rocks in granite. If you look closely at a piece of granite, you can easily see the crystals of feldspar. Feldspar forms in many colors such as pink, white and green.