\documentclass{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\usepackage{pgf-pie}
\begin{document}
\begin{tikzpicture}
    \pie[text=pin, sum=auto]{
        47/O,
28/Si,
8/Al,
5/Fe,
12/rest
    }
    \node [above=3mm, font=\large] at (current bounding box.north) {Percentage Abundance in crust};
\end{tikzpicture}
\end{document}