Is there a black 'dot' symbol that I can use?

Question

I want something like this:

gh $\blackdot$ On

I am aware of cdot but this needs to be much bolder.

Answer 1

Since \bullet is likely too bold, one can scale it to suit:

\documentclass{article}
\usepackage{graphicx}
\newcommand\sbullet[1][.5]{\mathbin{\vcenter{\hbox{\scalebox{#1}{$\bullet$}}}}}
\begin{document}
$A
\cdot A 
\sbullet A 
\sbullet[.75] A 
\bullet A$
\end{document}

If it is needed at the smaller mathstyles,

\documentclass{article}
\usepackage{graphicx,scalerel}
\newcommand\sbullet[1][.5]{\mathbin{\ThisStyle{\vcenter{\hbox{%
  \scalebox{#1}{$\SavedStyle\bullet$}}}}}%
}
\begin{document}
$A
\cdot A 
\sbullet A 
\sbullet[.75] A 
\bullet A$

$\scriptstyle A
\cdot A 
\sbullet A 
\sbullet[.75] A 
\bullet A$

$\scriptscriptstyle A
\cdot A 
\sbullet A 
\sbullet[.75] A 
\bullet A$
\end{document}