Crust (geology) depth, reaching values typically in the range from about to at the boundary with the underlying mantle. The temperature increases by as much as for every kilometer locally in the upper part of the crust, but the geothermal gradient is smaller in deeper crust. The continental crust has an average composition similar to that of andesite. The most abundant minerals in Earth's continental crust are feldspars, which make up about 41% of the crust by weight, followed by quartz at 12%, and pyroxenes at 11%. Continental crust is enriched in incompatible elements compared to the basaltic ocean crust and much
Primary minerals in the acidic igneous rocks and a second group of accessory minerals which were formed by deposition from the residual mother liquors. Modern soil science offers the following definition: "Primary Minerals: The thickness of the earth's crust varies from 10 km under the ocean to 30 km under the continents. Of the 88 naturally occurring elements on earth, only 8 make [up] most of the crust. The earth's crust and soils are dominated by the silicic acid in combination with Na, Al, K, Ca, Fe and O ions. ...Those elements are components of primary minerals, whereas primary minerals are components