| − | The '''silicates''' constitute the largest and commonest class of [[minerals]]. They are [[translucent]], at least in thin splinters, and on the average are lower in [[specific gravity]] and harder than most minerals. [[Water]] is present in a number of them, especially in the [[zeolites]], where it is loosely bound. In other species, water is strongly held and cannot be removed without destroying the mineral. Regardless of their complex nature, silicates all contain the [[silicate]] [[atomic structure]], whose fundamental building block is the [[tetrahedron]], in which one [[silicon]] [[atom]] is surrounded by four equally spaced [[oxygen]] atoms. The structure of the tetrahedron corresponds to the four-sided tetrahedron in the [[isometric]] [[crystal system]]. The silicon atom is inside the tetrahedron at the center, and the oxygen atoms occupy the four corners of the tetrahedron. The number and manner of linking of the silicon-oxygen tetrahedrons are the basis upon which the different silicate structures are formed. Chesterman, p. 501 | + | The '''silicates''' constitute the largest and most common class of [[minerals]]. They are [[translucent]], at least in thin splinters, and on the average are lower in [[specific gravity]] and harder than most minerals. [[Water]] is present in a number of them, especially in the [[zeolites]], where it is loosely bound. In other varieties, water is strongly held and cannot be removed without destroying the mineral. Regardless of their complex nature, silicates all contain the [[silicate]] [[atomic structure]], whose fundamental building block is the [[tetrahedron]], in which one [[silicon]] [[atom]] in the center is surrounded by four equally spaced [[oxygen]] atoms. The structure of the tetrahedron corresponds to the four-sided tetrahedron in the [[isometric]] [[crystal system]]. The number and manner of linking of the silicon-oxygen tetrahedrons are the basis upon which the different silicate structures are formed. <Ref>Chesterman, Charles W. ''The Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf: New York (1987) p. 501</ref> |