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
Sulfate crust into the atmosphere. Sulfate crust Sulfate crust is a zone observed in the axial (central) parts of burning coal dumps and related sites. It is a zone built mainly by anhydrous sulfate minerals, such as godovikovite and millosevichite. The outer zone can easily be hydrated giving rise to minerals like tschermigite and alunogen. The zone forms due to interaction with hot (even around 600 °C) coal-derived gases (mainly NH and SO) with the "sterile" material (i.e. shales and other rocks serving as the source of Al, Fe, Ca and other cations) in case of the lack of vents for the