Do you mean the part with the troglodytes? Is it one of those ?s or is it a random find in their storage area?
Yes it's in one of those rooms. I've been told that a room with glafire deposits is only view able if you have 15 perception. I have 20 perception so that's probably why it was so easy for me. If you still can't find any I recommend leveling up ur perception or editing ur character with saveeditonline to find the room with the deposits