Potassium lithosphere

The lithosphere consists primarily of rocks and minerals. Some of the important classes of metal compounds found in the lithosphere are oxides, sulfides, silicates, phosphates, and carbonates. The atmosphere surrounding the earth contains oxygen, so several metals such as iron, aluminum, tin, magnesium, and chromium are found in nature as the oxides. Sulfur is found in many places in the earth s crust (particularly in regions where there is volcanic activity), so some metals are found combined with sulfur as metal sulfides. Metals found as sulfides include copper, silver, nickel, mercury, zinc, and lead. A few metals, especially sodium, potassium, and magnesium, are found as the chlorides. Several carbonates and phosphates occur in the lithosphere, and calcium carbonate and calcium phosphate are particularly important minerals. 

Of the iron meteorites 99.22% of the material is made up of even nmn-bered elements, and of the stone meteorites, 97.50%. While the results for the earth s litho here are not so striking, they still show the same general tendency very strongly for, of the six most abundant elements, only aluminum is odd numbered, and the elements of even atomic number make up about 86% of the material. The only odd numbered elements other than hydrogen present in the lithosphere in amounts over 0.2% are aluminum, sodium, and potassium. 

It is easy to see too that most of the material has been used up in the formation of the lighter elements. Table 2 shows that in ffie meteorites the most abundant elements are oxygen in series 2, the elemdits of series 3 except neon, and the members of the first eighth gtoiq> triad (iron, cobalt, nickel). Clarke has found that just these same elements are the most abundant in the lithosphere, althou in the litho here potassium and calcium in series 4 are also moderately abundant. If the litho here were considered alone it might be considered that the abun-... 

Radioactive substances are widely distributed on the earth. Some are found in the atmosphere, but the major part is present in the lithosphere. The most important ones are the ores of uranium and thorium, and potassium salts, including the radioactive decay products of uranium and thorium. Uranium and thorium are common elements in nature. Their concentrations in granite are about 4 and 13mg/kg, respectively, and the concentration of uranium in seawater is about 3 pg/l. Some uranium and thorium minerals are listed in Table 1.1. The most unportant uranium mineral is pitchblende (UsOs). Uranium is also found in mica. The most important thorium mineral is monazite, which contains between about 0.1 and 15% Th. 

The abundances of these potassic hydrous phases, and hence the amount of water they can host, are limited by the potassium content of the mantle, but they are of considerable interest because of their high thermal stability. Depending on the precise mantle geotherm (adiabat) assumed, these hydrous phases may be stable in convecting mantle as well as in the cooler portions of the mantle such as the subcontinental lithosphere. This stability to high temperatures provides a mechanism not only to transport water into the mantle by subduction, but also to retain it. In this respect, the potassic hydrous phases contrast with the hydrous magnesium-rich phases, as outlined below. 

Sodium and potassium are in high abundance (2.6% and 2.4%) in the lithosphere and occur in large deposits of sodium chloride and carnallite, KC1 MgCl2 6H20. Lithium, rubidium and cesium have much lower abundances and occur mainly in a few silicate minerals. 

Rocks and Soils Potassium is a major element of the lithosphere with an average level of 24.1-25.9 g kg (Falbe and Regitz... 

The first marginally successful synthesis of elemental silicon was carried out in 1811 by Joseph Louis Gay-Lussac and Louis J. Thenard, who passed silicon fluoride over heated potassium. However, a much more successful method was used by Swedish chemist Jons Jacob Berzelius in 1824, which involved the reduction of potassium fluorosilicate with metallic potassium. The element silicon was eventually recognized to he one of the most abundant in the lithosphere, that is, the crust of the Earth. Remarkably, even at that early stage, a debate developed as to whether silicon was a metal or an insulator, with Berzelius taking the view that... 

Today, the more external part of the crust or lithosphere constitutes the superficial covering of the earth. Two kinds of crust are easily distinguished by composition, thickness and consistency continental crust and oceanic crust. Continental crust has a thickness that, in mountain chains, may reach 40 kilometers. It is composed mainly of metamorphic rock and igneous blocks enriched with potassium, uranium, thorium and silicon. This forms the diffuse granitic bedrock of 45 % of the land surface of the earth. The oceanic crust has a more modest thickness, in the order of 5-6 kilometers, and is made up of basaltic blocks composed of silicates enriched with aluminium, iron and manganese. It is continuously renewed along mid-ocean ridges (cf Table 2.2). 

Some elements do not form their own minerals but are present in the minerals of other elements. For example, gallium has many similarities with aluminum and is widely present in aluminum minerals. In the same way, the alkali metal rubidium is present in practically all potassium minerals. The element germanium ( eka-sil-icon ) is very like silicon. That is why the element is finely scattered among the silicates in the upper lithosphere. 

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