What types of metal dampen magic? I've heard of lead and gorgon's blood stopping teleports. What other metals block magic effects such as fire, ice, lightining, etc.?
There are no specific metals named, besides lead
A number of spells (Detect Evil and Good, Detect Magic, Detect Poison and Disease) have this exact wording in them:
The spell can penetrate most barriers, but it is blocked by 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt.
Message has similar wording:
Magical silence, 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood blocks the spell.
Detect Thoughts can pierce up to 2 inches of metal:
The spell can penetrate barriers, but 2 feet of rock, 2 inches of any metal other than lead, or a thin sheet of lead blocks you.
Thus, there no named metals for the purposes of blocking magic: lead is the best, and every other metal is equivalent. However, metals mostly block detection and communication spells--there is no metal that inherently blocks damaging effects like fire and ice. You could get full cover behind a wall of metal, but then it's the full cover protecting you, not any property of the metal.