Demon's Souls Ore

Hi guys...
Since my last toon got kind of glitched I decided to start a fresh one.
I got a lucky drop from one of the black skellies in 4-1 right from the start: an Uchigatana.
I've been upgrading it and now it's +6 but need more sharpstone chunks to level it further.
I already killed the crystal lizards in world 2-2 and they don't appear anymore and any other mob drops dragonstone or greystone only.
By any chance could you guys tell me what is the best mob to farm sharpstone chunks?
I would really appreciate the help.

The uchi is better if you upgrade it to sharp using bladestone, it gets S scaling in Dex.

Ohhh, ok. Thanks Wyrm. But now the thing is that I have to downgrade my Uchi first in order to upgrade it with bladestone... Right?
Honestly I find upgrading weapons in Demon's a little more annoying than in Dark with all this different types of Ore.