major silicates make up more than 90 percent of the minerals in earth’s crust a compound of...
TRANSCRIPT
Mineral Groups
Major SilicatesMake 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
QuartzMade 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
FeldsparsMake 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 SilicatesPyroxene
Mica
Amphibole
Kaolinite
Carbonate FamilyMade 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 FamilyCombined 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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