Watch out those rocks can get to be addicting...
As some said I've shot a few critters with stone points, the biggest being 1500# bison down thru elk, several deer, cougar, sheep and turkey. Out of probably 30 or so points shot into critters as long as I did my part right they performed just fine. Many times you will break or chip a point but I believe in all except a couple cases the breakage was caused by hitting bone on the off side of the animal. Now it also goes without saying that if you hit a large bone on entry the outcome isn't going to be pretty...
The point design didn't seem to be as important as the material it was made out of. Don't want to cause any arguments and I've used obsidian plenty so I'll only say there are several materials that are tougher and stronger for our purposes....
I've given away most of em but here are some examples for you to look at...
The one at about 8 o-clock is actually made from bison leg bone.
Good luck Jim and take lots of pics...