Mica Minerals. Feldspar is the most common mineral in the Earth s crust, so you are very likely to find it in the rocks you collect! It is found it all of the three rock types, but is most common in intrusive igneous ...more.hat means the rocks in your backyard probably have common minerals in them that you can identify. Minerals are divided into different groups based on their chemistry. The most common mineral group on Earth is the silicate minerals, which all have the elements silica and oxygen as their main ingredients.