In chemistry, a silicate is a chemical compound consisting of one or more central silicon atoms that are surrounded by electronegative anions.
The most common silicate species consist of silicon with oxygen as the anion. Silicate anions, with a negative net electrical charge, must have that charge balanced by other cations to make an electrically neutral compound.
In geology and planetary science, 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