  We show that the~braneworld rotating Kerr--Newman black hole and naked
singularity spacetimes with both positive and negative braneworld tidal charge
parameter can be separated into fourteen classes according to properties of
circular geodesics governing the~Keplerian accretion. We determine efficiency
of the~Keplerian accretion disks for all braneworld Kerr--Newman spacetimes. We
demonstrate occurrence of an~infinitely deep gravitational potential in
Kerr--Newman naked singularity spacetimes having the~braneworld dimensionless
tidal charge $b \in (1/4,1)$ and the~dimensionless spin $a \in
(2\sqrt{b}-\sqrt{b(4b-1)},2\sqrt{b}+\sqrt{b(4b-1)})$, implying unbound
efficiency of the~Keplerian accretion and possibility to extract the~whole
naked singularity mass. Therefore, we call them braneworld "mining-unstable"
Kerr--Newman naked singularity spacetimes. Fundamental restriction on
the~relevance of the~extraordinary but fully classical phenomenon of the~mining
instability is given by validity of the~assumption of geodesic motion of
the~accreting matter.
