Was this a flaw in the stone?

["George Graham" <georgergraham@zzzzzzzzzzz>]

Ad Sach,
Your stone must have had an existing crack. You couldn't have split a clean
piece all the way through using a point. Take a close look at all your stone
and look for fissures and cracks. Spray a little water on and watch as it
dries will help you spot a crack. Also look for a dirty line in the stone,
 from dirt and dust that helps identify a flaw. A crack doesn't have to run
all the way through. The break may only appear to go a few inches deep, and
only need a little pressure to keep running right through.
What to do with a flaw is the question.
Option 1, it the flaw seems to go very deep, go ahead and force the crack to
run its course, which you have done. Or call your supplier to gripe to him
for selling you flawed stone. If I ordered a block for a commissioned job,
and got a fractured stone I'd be looking for a replacement. A good stone man
can spot a crack, and should know what he is selling. If you bought "as is"
and did not pay a premium price, I'd say you were not ripped off.
Option 2, a shallow crack can sometimes be cleaned out by breaking out the
surrounding stone. If its on a corner or edge you can easily break it out.
In any case you have to work perpendicular to the plane of the flaw. Any
carving that goes with the line will only push the flaw deeper into the
stone. If you drive a chisel straight into the flaw you are basically
wedging the crack apart. Which appears to be what you did when your chisel
stuck in the stone. Anytime a stone carving chisel sticks in a  stone ,
damage has been done and all you can do figure out how much.
Finally, where ever 2 different colors come together  , especially when
there is a clear difference in texture and color, you are dealing with a
natural weakness where a major split can happen. Just work across the grain
, not with it.
Good luck, and keep your chisels sharp.
George Graham