Metamorphosed rocks composed largely of quartz are known as quartzite. Agate, chert, flint, and jasper are microcrystalline forms of quartz. Amethyst and Citrine are crystalline quartz with impurities providing the color. Economic uses of quartz include the glass and electronics industry, gemstones, and newage. Carbonates occur in all types of rocks, although more rarely in igneous rocks.
Most carbonates are secondary in origin, and react with HCl.
The Oxides consist of a metal and an oxygen, They generally have simple crystal structures and varied physical properties. Primary oxides, which tend to be harder, form within the earth most often when liquid rock is solidifying. Secondary oxides are more common and form usuually from weathering of other minerals. Bauxite and Uranite are important ores for Aluminum and Uranium, respectively. Hematite is the most important ore of iron.