The six classes of non-silicate minerals are oxides, sulfides, carbonates, sulfates, halides and phosphates. Non-silicate minerals are defined as substances within the Earth that do not contain silicon and are less complex than silicate minerals such as quartz and sand. Minerals are based on the type of anion, or negatively charged ion, within the substance.
Oxides contain oxygen as the anion. These minerals include corundum, hematite, magnetite, chromite and limenite. Corundum is one of the hardest substances known to humanity and is made of aluminum and oxygen. Gems of corundum include rubies and sapphires. Hematite and magnetite are iron ores.
Sulfides and sulfates both contain sulfur; the difference is that sulfates also contain oxygen bound to sulfur, whereas sulfides just contain sulfur atoms. Pyrite, galena, chalcopyrite and bornite contain sulfides. Sulfates include gypsum, anhydrite and barite.
Carbonate minerals consist of carbon and oxygen atoms as anions. Calcite, dolomite, malchite and azurite are common carbonates. Some of these minerals produce bubbles when hydrochloric acid touches them. Phosphates consist of phosphorous bound to oxygen atoms. Apatite and turquoise are two common phosphate minerals.
Halide minerals contain fluorine or chlorine. Halite, or salt, is one of the most common halide minerals in the Earth. Fluorite and sylvite also contain halide gases.