Rocks and Minerals The Silicate Minerals: The silica tetrahedron and Earth's most common minerals by Anne E. Egger, Ph.D. Reading Quiz Teach with this 1. The building block of the silicate minerals is the silica tetrahedron, represented by the chemical formula _________. (Si4O)4+ (SiO4)4- SiO2 Si-O 2. Silicate minerals are subdivided into groups based on their chemical composition physical properties atomic structures abundance in the crust 3. When silica tetrahedra polymerize, they share one or more of their oxygen molecules, so that the total number of oxygen cations per silicon anion decreases. true false 4. Why was the development of X-ray diffraction (XRD) so important to the study of minerals in general, including the silicates? XRD can determine the exact chemical composition of minerals. XRD can be used to determine the distances between atoms. XRD is able to break the Si-O bond, which is very strong. XRD can distinguish between silicates and non-silicates. 5. Which of the following describes the structure of hornblende? isolated tetrahedra single chain double chain sheet 6. Which of the following describes the structure of olivine? isolated tetrahedra single chain double chain sheet 7. Which of the following describes the structure of plagioclase feldspar? isolated tetrahedra single chain sheet framework 8. Which of the following describes the structure of pyroxenes? isolated tetrahedra single chain sheet framework 9. Which of the following describes the structure of muscovite? single chain double chain sheet framework 10. Feldspars and quartz have a similar structure, but ______ replaces Si4+ in some of the tetrahedra. Al3+ K+ Ca2+ Na+ 11. Muscovite breaks easily into very thin layers. Why is this the case? It is a double-chain silicate. It is a framework silicate. It is a sheet silicate. It is a silicate mineral. 12. Quartz and feldspar are both framework silicates and they are both very hard. This is because silicon is a hard element, so silicates are hard. there are no impurities in the framework silicates. there are strong bonds in all directions in the framework silicates. there is less oxygen in the framework silicates, so they are stronger. Score Quiz
