Hi Bill

Impact, is the best way to break the stones, and a retainer is needed
to keep the grit from disappearing, I haven't done much of this, but a
set of large bolts and a nut would work, just like this, the large
bolt with the nut on only a thread or two, some small stone in the nut
and than screw the other bolt down onto the stone, tighten and hammer,
repeat, repeat, the hammer hits will crush the stone, and it's easier
controlling the size they will get crushed to, but you do need some
large bolts and thick nut to start of with.
Of course a pipe with a metal plug welded in one side, and a fitting
steel rod to use as a ram or hit with a hammer would do also, but you
might end up with just colored dust that way.

Have fun and take care
Leo Van Der Loo

On Jul 9, 9:26 am, william kossack wrote:
I use crushed stone such as Turquoise and Malachite on some of my
turnings. The cost for already crushed stone ranges from $10 and ounce
to $20 an ounce.

I've purchased some nuggets and I was wondering how to best crush it
myself. Anyone have a simple solution?

PS I also have some blue lapis and garnet which are much harder.
Anything I use would have to be tough. The only way I've been able to
crush some of the lapis is with a sledge hammer on a rail road track but
the bag shredded.