Beach sand is mostly silica.
Deposited silicon dioxide, almost always by CVD approaches, is almost as old as thermal growth on the substrate, and has been employed in various ways in IC fabrication due to its familiarity, versatility, and reliability. Let us examine this interesting material. Furthermore, rotation of the bond about the axis is almost completely free. Essentially all deposited and thermally grown oxides in semiconductor processing are amorphous. Unlike e.g. amorphous silicon, amorphous silicon dioxide will not crystallize upon annealing at normal temperatures.