I just took a fascinating spin through just about every D&D source book I own searching for elfin chain, I cannot find it in OD&D (v1-3 and S1), Holmes, B/X, nor the 1st edition AD&D DMG. I did find it in my 2nd edition AD&D DMG, and then discovered it as well in Unearthed Arcana. Is this really the first appearance of the amazing light-weight armor? It always struck me as such an iconic piece of treasure, I really expected it to exist in earlier versions of the game.
More troubling though is the dates here. Unearthed Arcana was printed in 1985. However, the whole reason I went digging for this item was that I was transcribing the pre-gen characters from A1 to character sheets, and noticed one of them wears it. A1 was printed five years earlier, in 1980, so clearly the item existed well before UA hit the shelves. Am I missing something here?