Solid mineral portion of the soil

The origin of the mineral portion. Rocks covering the earth s surface, which are submitted to intense weathering, may be divided into three main groups, igneous, sedimentary and metamorphic rocks. 

Sedimented rocks were formed from transported products of weathering of igneous and metamorphic rocks. Depending on the origin and mechanism of the formation, the sedimented rocks may be categorized as follows  

Sedimented rocks are frequently characterized by a remarkably stratified and very heterogeneous (or sometimes, in contrast, rather uniform) grainy 

Metamorphic rocks were formed by a secondary conversion of igneous and sedimented rocks, due to certain geological tectonic processes. The pressure, temperature, and chemical effects, particularly effects of gases and thermal solutions were the main factors in these conversions. The texture of metamorphic rocks may be characterized by the presence of layers or scales. Typical metamorphic rocks are gneisses, mica-schists, serpentines, crystalline limestones and crystalline dolomites. 

Basic minerals contributing to the soil formation. The rocks consist of minerals, each of them being characterized by a certain chemical composition and arrangement of the crystalline structure. The basic units of the mineral crystalline structure are not molecules, and thus, electrostatic forces, which are not restricted by particular valence bonds, play the most important role in binding relevant ions and their groups. Coordination bonds occur in minerals. The arrangement of basic structural units is go- 

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