In chemistry, a silicate is a compound
containing an anion in which one or more central silicon atoms are
surrounded by electronegative ligands. This definition is broad enough to
include species such as hexafluorosilicate ("fluorosilicate"),
[SiF6]2-, but the silicate species that are encountered most
often consist of silicon with oxygen as the ligand. Silicate anions, with a
negative net electrical charge, must have that charge balanced by other
cations to make an electrically neutral compound.
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.
