I think my mage found a site he shouldnt have?

[onomastikon]

I set my Master Engineer to search for magic sites, and he got one which also had death gems. How can that be? Or is it the fact that mages find sites in general, and if they find one which has two types (say fire and death) and they only know fire, they find the entire site?

Actually, are there any prerequisites for finding those "recruiting" sites (like where you can recruit a witch or other neat casters)?

thanks