The idea linked below proposed using piezoelectric elements in a rock chisel to increase its effectiveness.
The MaxCo. R&D department looked at this, and - as one man - said "Pshaw!" This was probably because they had all recently been on a company-sponsored Outdated Ejaculations Awareness course.
They then got down to work, and came up with something better.
A great many minerals are, in fact, piezoelectric. Quartz is an excellent example, and I'm sure I could think of more if I could think of more. But most rocks contain quartz grains.
It follows, thereforehence, that a brief pulse of high voltage, applied across a quartz-containing rock (think granite, basalt, sandstone, schist [no, schist]) should create a nice little shock wave more than capable of propagating a crack.
MaxCo's Really Excellent Chisel For Rock (we have a new marketing team - they thought the acronym would be "racey and viral"), therefore, is designed to deliver a brief, high-voltage pulse coincident with the hammer blow, to more increase and greaten its effect. Ironically, it may be simplest to generate the voltage pulse by means of a piezoelectric element, but located in the head of the chisel rather than (as with inferior piezoelectric rock chisels) in the tip.