13.8: Structures and Chemistry of Nonsilicates

Having discussed silicate structures, we could go on and discuss structures in other mineral groups. However, unless we wanted to go into great detail, such a discussion would not be particularly fruitful for several reasons. First, because silicate structures are largely ionic, they are simpler and more regular than those of most other mineral groups. And in our discussion of silicate structures, we ignored or glossed over some complications that become very important in other kinds of minerals. Second, for some mineral groups we cannot make meaningful generalizations or categorize structures in a useful way. For example, the sulfide minerals involve structures that are covalent or metallic, or both. Sulfur may have any of several valences, and sulfide structures involve many different coordination polyhedra, layers, clusters, and other complex structural units. Thus, generalizations made about structure types will inevitably be too detailed or not detailed enough for different purposes. So, instead of worrying about the details of structure and chemistry of all mineral groups, we note that the same principles that apply to silicates also apply to other minerals.