A silicate mineral having chemical formula ${\mathrm{Ca}}_2{\mathrm{Mg}}_{\mathrm{x}}{\mathrm{Si}}_8{\mathrm{O}}_{22}(\mathrm{OH}{)}_2$ and known as tremolite predict the value of x:

The value of x can be calculated as,

$\begin{array}{l}{\mathrm{Ca}}_2{\mathrm{Mg}}_x{\mathrm{Si}}_8{\mathrm{O}}_{22}(\mathrm{OH}{)}_2\\ \Rightarrow 2\times (+2)+x(+2)+8(+4)+22(-2)+2(-1)=0\end{array}$

Thus, the correct option is D.