Mineral Groups

Major Silicates Make up more than 90 percent of the minerals in Earth’s crust A compound of silicon, oxygen and usually one or more metallic elements, such as aluminum or iron Silica tetrahedron structure, which is four oxygen atoms bonded to a central silicon atom

Quartz Made entirely of tightly bound silica tetrahedra. Chemical formula SiO2 Glassy or greasy luster Pure Quartz is colourless or white Hardness of 7 on Mohs scale Only second most abundant on Earth’s crust

Feldspars Make up about 60 percent of Earth’s crust Two directions of cleavage Hardness of 6 Pearly luster Some of the silicon atoms in the tetrahedral structure are replaced by aluminum The net charge due to this exchange causes the addition of other metals (K, Na, and Ca)

Other Silicates Pyroxene Mica Amphibole Kaolinite

Carbonate Family Made of negatively charged carbonate ions (CO32-) bonded to positive metal ions Limestone and marble consist almost entirely of carbonate minerals Calcite (Calcium Carbonate) and dolomite (Calcium magnesium carbonate) are two examples

Oxide and Sulfide Family Combined with a iron Not as common as silicates or carbonates, but very important economically Examples are Hematite (most common iron oxide), Magnetite (black iron oxide), and Pyrite (most common sulfide mineral, iron sulfide)

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