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 number seven on their "Top 10 Online Game Picks", remarking, "It has depth, community, and racks up 500,000 hours of use a month. Someone must like this game." In May 2010, "GemStone IV - Shattered" was released by Simutronics. It allows unrestricted player-vs-player combat and has no policy against automated play. GemStone IV GemStone IV is a multiplayer text-based online role-playing video game (often known as a MUD) produced by Simutronics. Players control characters in a High Fantasy game world named "Elanthia". The first playable version of the game was known as "GemStone ][" and was launched in April 1988