I am aware of cdot but this needs to be much bolder.
Best Answer
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}
Following David Carlisle's suggestion here's a TikZ solution:
\documentclass{standalone}
\usepackage{tikz}
% w/o following space!
\newcommand{\quem}{\tikz[baseline=(wi.base)]{\node[fill=black,rotate=45,inner sep=.1ex, text height=1.8ex, text width=1.8ex] {};%
\node[ font=\color{white}] (wi) {?};}}
\begin{document}
Some \quem Text
\end{document}
You may alter the size of the black triangle by playing with inner sep and keep in mind that there is no space an the end of the macro.
Best Answer
Since
\bullet
is likely too bold, one can scale it to suit:If it is needed at the smaller mathstyles,