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
USS Aquamarine (PYc-7) USS Aquamarine (PYc-7) USS "Aquamarine" (PYc-7) was a patrol boat in the United States Navy during World War II. Later known as Miss Ann, the ship was listed on the U.S. National Register of Historic Places in 1998. "Aquamarine" was built in 1925 by Pusey and Jones Corporation, Wilmington, Delaware under the name "Siele", the private yacht of John H. French. In 1936 she was sold to Robert H. Wolfe, of Columbus, Ohio, and renamed "Seawolf". "Seawolf" was bought by the Navy on 13 January 1941, and commissioned on 9 April 1941, Lieutenant G. A. Lange in command. She was