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
GemStone IV named "Avalon" is available for Mac OS X. No official Linux client exists. "GemStone" was first demonstrated to GEnie in 1987 before Simutronics was officially incorporated. It was only used as a demonstration model and was never available to the general subscribers. "GemStone ][" was released in April 1988 to GEnie customers. However, "GemStone ][" was very short-lived, and "GemStone III" went into open beta testing in December 1989, officially launching on February 1, 1990. The transition from "][" to "III" maintained significant portions of the environment, but not all, and character records were not maintained over the transition, requiring