How to avoid spaces after figure

Question

Im trying to make the rules equally spaced

\begin{center}
\rule{\textwidth}{.6pt}
\end{center}

\begin{figure}[H]
    \centering
    \rule{0.5cm}{0.5cm}
\end{figure}

\begin{center}
\rule{\textwidth}{.6pt}
\end{center}

Answer 1

It's better to use a low level primitive, namely \hrule:

\documentclass{article}

\begin{document}

\begin{center}
\hrule height 0.6pt

\vspace{1cm}

\rule{0.5cm}{0.5cm}

\vspace{1cm}

\hrule height 0.6pt
\end{center}

\end{document}

Sorry for the low accuracy, but that's all Adobe Reader provides.

Answer 2

Also possible with tikz:

\documentclass{article}
\usepackage{tikz}
\begin{document}

\noindent%
\begin{tikzpicture}
\draw (0, 0) -- ++(\linewidth,0)
      (0,-2) -- ++(\linewidth,0);
\node [draw,fill,minimum size=.5cm] at (\linewidth/2,-1){};
\end{tikzpicture}

\end{document}