Aqua regia (Latin: Royal Water) is one of the strongest acids known in Chemistry, and is capable of dissolving gold and platinum.
My copy of the Oxford science dictionary goes on to say (under the entry: Aqua regia) that metallic silver does not dissolve in aqua regia. ItMorever it does not mention any other examples of aqua regia-resistant metals. Further down, it mentions that silver's invulnerability to aqua regia is due to the formation of a protective silver chloride coating on the metal, which serves to protect the metal from further decomposition.
However, this Wikipedia article claims:
...aqua regia does not dissolve or corrode silver...
This, I find contradictory to the dictionary's "formation of silver chloride" claim.
So,
What metals (elemental, forget alloys) are neither attacked by nor dissolved in (freshly prepared) aqua regia?
What makes those metals that don't dissolve or corrode in aqua regia so impervious to the acid?
Does silver metal actually develop a silver chloride layer on exposure to aqua regia? If so, would that mean the Wikipedia article is incorrect?**
