The building blocks of the silicate minerals is called the what?

Silicate tetrahedra. The tetrahedra are spanned by oxigen atoms, and right in the middle, there is a silicon atom. The chemical formula for one silicate tetrahedron is SiO4

The actual rate between silicon and oxigen can change as the tetrahedra are linked together, as different tetrahedra can share an oxigen atom with eachother.