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
Alkaline earth metal magnesite, and dolomite. Common calcium-containing minerals are chalk, limestone, gypsum, and anhydrite. Strontium is the fifteenth-most-abundant element in the Earth's crust. The principal minerals are celestite and strontianite. Barium is slightly less common, much of it in the mineral barite. Radium, being a decay product of uranium, is found in all uranium-bearing ores. Due to its relatively short half-life, radium from the Earth's early history has decayed, and present-day samples have all come from the much slower decay of uranium. Most beryllium is extracted from beryllium hydroxide. One production method is sintering, done by mixing beryl, sodium fluorosilicate, and soda