Silicate minerals form over 90 percent of Earth's crust, they contain silicon (Si) and oxygen (O). Silicates are further broken down into six categories based on the complexity of their structure. Cyclosilicates Cyclosilicates (ring silicates) are based on three, four or six tetrahedrons joined together in a ring. Six is the most common framework. An example of this is beryl (emerald, aquamarine, tourmaline).
