Iliac crest pain is not that common in the general population, but it is frequent in older individuals, runners (and athletes in general), lower back pain sufferersâ¦ But that doesn`t mean âregularâ people like you and me can`t experience it from time to time!
The mantle is composed of iron-magnesium silicates, and the crust is composed of roughly 5 percent iron. All together, iron makes up an estimated 35 percent of the Earth's mass. Oxygen. Oxygen, the second most abundant element on Earth, is found mainly in the crust.
Building Blocks of The Earthâs Crust. Silicates are the most widespread of the minerals. They are made up of oxygen and silicon the number one and number two most abundant elements in the earth's crust. By themselves they make up over 90% of the weight of the earthâs crust. Most rocks are composed mainly of this class of minerals. There are two forms of silicate when looking at their chemistry: