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 Publishing regarding Disney characters, and started publishing comic titles previously owned by Gemstone in the second half of 2009. Gemstone Publishing Gemstone Publishing is an American company that publishes comic book price guides. The company was formed by Diamond Comic Distributors President and Chief Executive Officer Steve Geppi in 1994 when he bought Overstreet. Gemstone published licensed Disney comic books from June 2003 until November 2008. The company has also reprinted EC Comics of the 1950s. BOOM! Kids acquired all comic publishing licenses regarding Disney characters in the second half of 2009. Gemstone's flagship publications were comic books featuring Disney characters;