I've reached the part where you are finding a hiding place for the
Dragon Bane sword and I just dropped down in the a section in the
disused mine shaft. I followed the path around and reached a gate
where it is asking me for the slate key. Apparently, I missed it
and I don't see anyway out. I've already used two keys (one brass
and the other bone I think).

Also, I have the Moor key, but don't know what to do with it. The
key hole in Darion says I can get 150 gold pieces, but I don't know
where to claim my prize.