Does silicon dioxide react with alkalis? In my science class, I have been taught that silica (silicon dioxide/sand) has three properties, namely


It does not react with water. 
It does not decompose with heat. 
It does not react with acid. 


However I think that if it does not react with acid, will it react with bases? I am just curious because if it does react, why does my textbook not say anything about that?
It really does react:
\begin{align}
\ce{4HF + SiO2 &amp;-&gt; SiF4 + 2 H2O}\\
\ce{SiF4 + 2 HF &amp;-&gt; H2[SiF6]}\\
\ce{SiO2 + 2 NaOH &amp;-&gt; Na2SiO3 + H2O}\\
\ce{SiO2 + 2 F2 &amp;-&gt; SiF4 + O2}\\
\ce{SiO2 + 2 C &amp;-&gt; Si + 2 CO}\\
\ce{(2,1)Na2O + (1,1)SiO2 &amp;-&gt; Na4SiO4/Na2SiO3}\\
\ce{SiO2 + Si &amp;-&gt; 2 SiO}
\end{align}