  By considering the concept of the modified Chaplygin gas (MCG) as a single
fluid model unifying dark energy and dark matter, we construct a static,
spherically charged black hole (BH) solution in the framework of General
Relativity. The $P-V$ criticality of the charged anti-de Sitter (AdS) BH with a
surrounding MCG is explored in the context of the extended phase space, where
the negative cosmological constant operates as a thermodynamical pressure. This
critical behavior shows that the small/large BH phase transition is analogous
to the van der Waals liquid/gas phase transition. Accordingly, along the $P-V$
phase spaces, we derive the BH equations of state and then numerically evaluate
the corresponding critical quantities. Similarly, critical exponents are
identified, along with outcomes demonstrating the scaling behavior of
thermodynamic quantities near criticality into a universal class. The use of
\emph{geometrothermodynamic} (GT) tools finally offers a new perspective on
discovering the critical phase transition point. At this stage, we apply a
class of GT tools, such as Weinhold, Ruppeiner, HPEM, and Quevedo classes I and
II. The findings are therefore non-trivial, as each GT class metric captures at
least either the physical limitation point or the phase transition critical
point. Overall, this paper provides a detailed study of the critical behavior
of the charged AdS BH with surrounding MCG.
