Silicate Rock and Minerals
In geology and astronomy, the term silicate is used to denote types of rock that consist predominantly of silicate minerals. On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that form and re-work the crust. These processes include partial melting, crystallization, fractionation, metamorphism, weathering and diagenesis. Living things also contribute to the silicate cycle near the Earth's surface. A type of plankton known as diatoms construct their exoskeletons, known as tests, from silica. The tests of dead diatoms are a major constituent of deep ocean sediment.
Silica, or silicon dioxide, SiO2, is sometimes considered a silicate, although it is the special case with no negative charge and no need for counter-ions. Silica is found in nature as the mineral quartz, and its polymorphs.
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Famous quotes containing the word rock:
“You have constantly urged the idea that you were persecuted because you did not come from West-Point, and you repeat it in these letters. This, my dear general, is I fear, the rock on which you have split.”
—Abraham Lincoln (1809–1865)