Latex sample bold greek

Using Bold Greek Letters in LaTeX

Bold Greek letters are available using boldsymbol in the amsmath package.

\documentclass{article}
\usepackage{amsmath}

\begin{document}
Let $\boldsymbol\alpha$ be a vector.  Call it $\boldsymbol\beta$.
\end{document}

(Note that this is not to be taken as an example of good mathematical exposition.)