Breaking down pyrite nuggets?

Can anyone recommend the best way to break down pyrite nuggets? I’m
looking to get smaller pieces from the big nuggets having originally
used the little pieces of pyrite from the bottom of the bag of
nuggets.

Any gem and mineral book should discuss cleavage planes. the Audubon
field guides for instance have a brief discussion of the various
types of cleavage relative to the gem and mineral kingdom replete
with diagrammatic arrows. So get out a cold chisel with a 1 inch face
and a good dead blow hammer and put on your eye protection, take it
outside and place the stones on a stump, or other absorbent
"pedestal" for lack of a better word and hit the material with enough
force just to break it on the plane indicated, but nowhere near
enough force to get your aggressions out ( if there are any!). You
may wrap the stone in a towel (once aligned within it -then strike
with the hammer) first to catch minute pieces. good luck…another
stone that may interest you is limonite after pyrite.
I would think the contrast has some design potential! RER.