Silicon and oxygen, the two most common chemical elements in the Earth's crust, combine as silicon dioxide to form the mineral quartz.
[COLOR=blue! important][COLOR=blue! important]Quartz[/color][/color] is the most abundant mineral in the Earth's crust. Quartz has been found in meteorites and in some rocks collected on the moon.
Quartz has the chemical formula SiO2. There are many varieties of quartz, which occurs in nearly all types of igneous, metamorphic and sedimentary rocks. It is an essential mineral in granites, granodiorites and rhyolites. Metamorphism of quartz-bearing igneous and sedimentary rocks typically increases the amount of quartz and its grain size.
Quartz is very resistant to weathering and, therefore, concentrates as sandstones and other detrital rocks. Most sands are weathered fragments of quartz. Sandstone and quartzite are the same materials that are re-lithified (compressed into rock).
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