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
Gemstones of Pakistan to their report, 29759 tons of quartz was produced in Mohmand agency in 2003-2004. However, the gemstone sector in the region is not developed and many resources have not been properly identified and exploited. The three mountain ranges of Gilgit-Baltistan; Himalayas, Hindukush, and Karakoram contain many minerals and gems including emerald, ruby, sapphire, aquamarine, moonstone, and amethyst. A number of other minerals are also found in the region such as peridot, tourmaline, topaz, garnet, red spinal, pargasite, diopside, sphene, apatite, azurite, rose quartz, and agate. In Swat, pale green to green coloured emeralds can be found in talc-carbonate schist. In