Summary
Contents
Subject index
This unique addition to reference literature provides an introduction to the major concepts and contemporary issues that are essential for students of environmental science and environmental studies to know. With over 200 entries authored by world-class names like Anthony Brazel, John Day and Edward Keller, this text is divided into six sections: Environmental Science, Environments, Paradigms & Concepts, Processes & Dynamics, Scales & Techniques, and Environmental Issues.
Minerals
Minerals
Most of the rocks in the Earth's crust consist of combinations of just 15 of the nearly 3600 known minerals. These ‘rock-forming’ minerals consist, in turn, of the most abundant elements by weight and volume in the Earth's crust (Table 40). Silica (SiO2)is an essential component in most of these minerals. Some minerals have a fixed composition (quartz and calcite), whereas the proportions of elements may vary in others (amphibole, pyroxene).
| Table 40 Common rock-forming minerals | ||
|---|---|---|
| Mineral | Composition | Comprises rocks |
| Plagioclase | NaAlSi3O6 − CaAl2Si2O6 | Basalt, andesite, granite, gabbro |
| K-feldspar | KAlSi3O8 | Granite |
| Olivine | (Mg,Fe)2SiO4 | Basalt, gabbro |
| Quartz | SiO2 | Granite, sandstone |
| Muscovite | KAl2(AlSi3O10)(OH,F)2 | Granite |
| Biotite | K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2 | Granite |
| Amphibole (hornblende) | Ca2(Mg,Fe)4Al(Si7Al)O22(OH,F)2 | Andesite |
| Pyroxene (augite) | (CA,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 | Andesite, basalt, gabbro |
| Calcite | CaCO3 | Limestone, marble |
| Dolomite | (Mg,Ca)CO3 | Dolostone |
| Gypsum | Ca(SO4) | Evaporite |
| Chlorite | (Mg,Fe)3(Si,Al)4O10•(Mg,Fe)3(OH)6 | Schist |
| Clay minerals | Al, (Mg, Fe) hydrous silicates | Shale |
| Alumino-silicates | Al2SiO5 | Schist |
| Garnet group | (Mg,Fe,Ca)3Al2Si3O12 | Schist, gneiss |
Rock-forming minerals are rarely found in the big, beautiful crystals prized by collectors, and their black or white colours seldom render them very exciting. As a result, many of the ...
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