Translations:Benutzer:Arian/Klett-Mini-Test/1093/en

The great number of elements that make up the substance-composition of magmatic intrusive and extrusive rocks are soil-forming and at the same time essential in large numbers for the thriving of plants. Here, in the soils and parent rocks, just as there in the plants and plant species, the proportion of these elements varies. The intrusive rocks of the granite series, for instance, show decreasing silica content from granite with approximately 80% SiO₂ through *syenite* (60%), *diorite* (55%) and *gabbro* (50–45%). Conversely, the content of iron, magnesium and calcium oxides increases to a multiple. In the porphyry series from quartz porphyry through porphyry, porphyrite to diabase or melaphyre, the same holds, as it does for the series of extrusive rocks from the silica-rich *liparite* through *phonolite*, *andesite* to basalt. On basalt plateaus one finds particularly fertile, mineral-rich soils. On account of its widespread occurrence and its rather basic mineral composition with 45% SiO₂, 10% FeO, 7% MgO, 10% CaO++ basalt furnishes the most widely applied rock dust. Here, in the broadly ranging elemental composition, the dominance of silica and of alumina (aluminium oxide, Al₂O₃), or respectively the force-potential that this particular composition has brought forth, is of great significance. The strict state of form of the crystal transforms itself into the colloidal, in which the substance is held in suspension between solid and liquid.