Re cutting psilomelane.....this can be a problem, especially if it
is the old CA material that is more manganese than pyrolucite. This
is one of my favorite stones (if there is any favortism) and I have
cut a lot of them.
I do not recommend using a continuous rim blade. It does not deliver
enough coolent to the kerf which will quickly load up and 'grab' the
blade. Use a segmented blade to preclude this. I do not recommend a
thin blade.....a .018 is a bit thin....try using a.020 or a.025 at
least. Again, this will preclude kerf build up and give a smoother
cut. By the way, do not expect to use water as a coolent with psi.
You need one of the special coolents such as KoolKut or Almag or some
If you are using a 5" blade you cannot cut a nodule much larger than
1" in thickness. The material is just too tough. Be sure the nodule
is held VERY firmly in a vise. The slightest movement will cause
binding. If you are hand holding the piece, back off periodically to
be sure you are not binding the blade.
One exception to above,....you might want to try the CBN 'meteorite'
blade sold by Graves Lapidary Co (www.gravescompany.com) (I work
there). It is a 6"x.012" (in addition to other sizes) blade that is
especially constructed just to cut materials such as meteorites and
If you intend to cab the psi... be sure to use loooots of water and
cut very slowly. Otherwise it will load up you wheels. But....the
results are absolutely stunning.
Cheers and happy cutting from Don at The Charles Belle Studio in SOFL
where simple elegance IS fine jewelry! @coralnut2