\documentclass{article}
% translate with >> pdflatex -shell-escape <file>

% This file is an extract of the PGFPLOTS manual, copyright by Christian Feuersaenger.
% 
% Feel free to use it as long as you cite the pgfplots manual properly.
%
% See
%   http://pgfplots.sourceforge.net/pgfplots.pdf
% for the complete manual.
%
% Any required input files (for <plot table> or <plot file> or the table package) can be downloaded
% at
% http://www.ctan.org/tex-archive/graphics/pgf/contrib/pgfplots/doc/latex/
% and
% http://www.ctan.org/tex-archive/graphics/pgf/contrib/pgfplots/doc/latex/plotdata/

\usepackage{pgfplots}
\pgfplotsset{compat=newest}

\pagestyle{empty}

\usepgfplotslibrary{ternary}
\usepackage{textcomp}

\begin{document}
\begin{tikzpicture}
\begin{ternaryaxis}
	\addplot3 coordinates {
	    (0.81,	0.19,	0.00)
	    (0.76,	0.17,	0.07)
	    (0.66,	0.16,	0.16)
	    (0.76,	0.07,	0.17)
	    (0.81,	0.00,	0.19)
	};

	\addplot3 coordinates {
	    (0.85,	0.15,	0.00)
	    (0.82,	0.13,	0.05)
	    (0.73,	0.14,	0.13)
	    (0.82,	0.06,	0.13)
	    (0.84,	0.00,	0.16)
	};
	\legend{$10$\textdegree, $20$\textdegree}
\end{ternaryaxis}
\end{tikzpicture}
\end{document}
