And how many obsidian mirrors were there in eighteenth-century England anyway?
Typical of Walpole that he also supplied a poetic epigram in this note:
Kelly was Dr Dee's Associate and is mentioned with this very Stone in Hudibras, Part 2. Canto 3 v.631. Kelly did all his feats upon The Devil's Looking-glass, a Stone.
This mirror is in the news because some scientists have run a sample of it through their elemental analyzer and discovered that it is from Mexico, likely the very same quarry at Pachuca from which the Aztecs got stone for their own mirrors. It looks like an Aztec mirror, and had long been supposed to be one, but this nails it down. Dee almost certainly knew where this mirror came from, since he was very involved in supporting the exploration of the New World and publishing the discoveries made there. I find that interesting. Did he think the mirror might be imbued with arcane devilry, or even soaked with the blood of human sacrifices? Or did he just think that the Aztecs had the best obsidian?