Thanks to Wyvern & Regis

Thank you for answering my message. But I am still stuck. I have searched the entire area. I found 2 crystals one behind the rocks the other in the spider nest.
I can't find the other one. Has anyone else had this problem? I don't want to start over, of course I don't have a save game before Dragonshire, I will from now on. Another area needing improvement.

The last crystal is a maze-like area with lots of chests...the Area can be found after you have talked with the dwarf-tinker....atlest as i remeber it

i found three crystal, 1) where the large scorpion is located (at the beginning when you enter the cave)
2) where the lava area (ie where the eels are....just on the other side of the lake)
3) where the queen spider is located.

Currently looking for the fourth one now.