The basic structural unit of feldspar, zeolites, mica, and asbestos is:

$$\begin{gathered} \mathrm{Feldspar}:{\mathrm{KAlSi}}_3{\mathrm{O}}_8-{\mathrm{NaAlSi}}_3{\mathrm{O}}_8-{\mathrm{CaA}}_2{\mathrm{ISi}}_3{\mathrm{O}}_8 \\ \mathrm{Zerolite}:{\mathrm{NaAlSi}}_2{\mathrm{O}}_{(}6.){\mathrm{H}}_2\mathrm{O} \\ \mathrm{Mica}:{\mathrm{KAlSiO}}_{1}0(\mathrm{OH}{)}_2 \\ \mathrm{Asbestos}:{\mathrm{Mg}}_3{\mathrm{Si}}_2{\mathrm{O}}_5\left(\mathrm{OH}{)}_4 \\ \mathrm{Thesearesilicateshavingbasicunit}\right({\mathrm{SiO}}_4{\left)}^{\right(}-4) \end{gathered}$$