Mirrors and Scrying

In 2021 X-ray fluorescence traced the British Museum's obsidian 'Dee mirror' to Pachuca in Aztec Mexico. Its link to John Dee rests on a label by Horace Walpole, its owner by about 1770.

Stuart Campbell, Elizabeth Healey, Yaroslav Kuzmin and Michael D. Glascock, 'The mirror, the magus and more: reflections on John Dee's obsidian mirror', Antiquity 95 (384), 2021, pp. 1547-1564

Gazing into a crystal, a mirror or a polished black stone to see visions or spirits.

Sources2 sources

Scholarship

Stuart Campbell, Elizabeth Healey, Yaroslav Kuzmin and Michael D. Glascock, The mirror, the magus and more: reflections on John Dee's obsidian mirror (Antiquity 95, no. 384), 2021, pp. 1547-1564XRF sourcing of the British Museum 'Dee mirror' to Pachuca obsidian, Mexico; its Dee attribution rests on Horace Walpole's label (owner by c. 1770).
Doubts have even been raised about how reliable its attribution to Dee is
Deborah E. Harkness, John Dee's Conversations with Angels: Cabala, Alchemy, and the End of Nature, 1999, pp. 158-159Dee's angel conversations through scryers and a crystal showstone (1581-1586, 1607), and his belief that the angels' language was Adam's divine language.
the divine language of the Book of Nature lost to humans since the days of Adam