Feldspar is a group of rock-forming tectosilicate minerals that contains calcium, potassium, or sodium and makes up more than half of the Earth’s core by weight. Its minerals are found to a large extent in igneous, sedimentary and metamorphic rocks around the world. These minerals are the basic components of these rocks, some of which are classified based on feldspar content. In most cases, these minerals are found naturally in matte shades of white to gray and pink to very dark gray and have a glassy shape. Because feldspars are made up of two plates divided into 90-degree intersections, parts of the pure crystals of these materials tend to form rectangular blocks with different ends. It is important to note that these rocks can be divided into two main groups: potassium feldspar and plagioclase.