I had not heard of the ‘black mirror‘ until the artist Karen Strang shared some of the story behind it.
This is from Southern Reporter and Cork Commercial Courier, 17 September 1856:
Claude Glass [Black mirror]
L0057559 Claude Lorrain mirror in shark skin case, believed at one ti Credit: Science Museum, London. Wellcome Images images@wellcome.ac.uk http://wellcomeimages.org Claude Lorrain mirror in shark skin case, believed at one time to be John Dee's scrying mirror. Front three quarter view. Case open. Graduated grey background. Published: - Copyrighted work available under Creative Commons Attribution only licence CC BY 4.0 http://creativecommons.org/licenses/by/4.0/