Silicon is the second most abundant element in the Earth’s crust and yes, that includes sand.
I should NOT have to tell anyone who graduated high school this, but silicon is only the base on which semiconductors are constructed. Look up "dopants", the small galaxy of other elements added to produce the desired properties. They include almost all of the metals in the periodic table. Without them there are no transistors, and hence no computers more sophisticated than the old UNIVAC, with its' thousands of vacuum tubes.