silicate minerals 

Silicates are minerals composed of the elements silicon (Si) and 
oxygen (O), alone or combined with other elements. Most minerals are 
silicates; more than 1,000 are known. Together, oxygen and silicon 
make up about 75 percent by weight of the crust, the Earth's outer 
shell. The crust, 10 to 70 km thick, is composed almost entirely of 
silicates. The surfaces of the Moon and of Mars, and probably the 
mantle zone within the Earth, are also composed of silicates. The most 
widely used construction materials--glass, ceramics, brick, concrete, 
and much building stone--consist entirely or mainly of silicates. Many 
highly prized gems, such as emerald, aquamarine, tourmaline, and 
topaz, as well as massive semiprecious stones such as agate, jasper, 
and chalcedony, are silicates.