With only an elementary school education, Garrett Morgan, born in Kentucky on March 4, 1877, began his career as a sewing-machine mechanic.
The most abundant elements in the Earth's crust are oxygen (46.6%) and silicon (27.7%). Minerals which combine these two elements are called silicates, and combined they are the most abundant minerals on the Earth. The silicates can be organized in terms of their chemical compositions and their crystal structures (indicated by the existance of cleavage planes). They most often contain members of the Big 8 elements.
In framework silicates, each silicon shares all four of its oxygen with adjacent silicon resulting in a three dimensional framework of strong covalent bonds. The simplest framework silicates is quartz which contains only silicon and oxygen.The feldspars are framework aluminum silicates. Since aluminum occupies the middle of some of the tetrahedra, other metals, namely K, Na and Ca are needed to balance the charge of the crystal.hus the relative amounts of oxygen, silicon and aluminum in the mineral increase, as the amount of iron, magnesium and calcium decrease. Silicate minerals rich in iron, magnesium or calcium are called mafic.