Mineral site, and from there further subdivided by the chemistry of the W site. The Y and Z sites can accommodate a variety of cations, especially various transition metals; this variability in structural transition metal content gives the tourmaline group greater variability in colour. Other cyclosilicates include beryl, AlBeSiO, whose varieties include the gemstones emerald (green) and aquamarine (bluish). Cordierite is structurally similar to beryl, and is a common metamorphic mineral. Sorosilicates, also termed disilicates, have tetrahedron-tetrahedron bonding at one oxygen, which results in a 2:7 ratio of silicon to oxygen. The resultant common structural element is the [SiO] group. The
Aquamarine (novel) from her six sisters, and is suffering from the chlorine in the pool. Hailey and Claire advise Aquamarine to return to the ocean, however she refuses, because of her new attachment to Raymond. Claire and Hailey read books that contain information pertaining to marine life-forms, trying to find an answer to Aquamarine's troubling conditions. They learn that mermaids cannot survive on land for more than a week. The necessity of returning Aquamarine to the ocean is thus made more urgent. In order to persuade Aquamarine to return to her home, Hailey and Claire arrange that she will spend one evening