Last Updated: Jan 06, 2017 Views: 50
I have not yet found an answer to your question about lapis lazuli and its use in dark mirrors. obsidian was often used.
I am sending some updated references to Claude Glasses (there is more in JSTOR, if you have access to the database in a local library); lapis; and solar microscopes.
I am hoping tomorrow to visit the library to see these books and periodicals, as I'm looking for information on black mirrorizing (these were used in solar microscopes as well as Lorraine Mirrors).
Would it be possible to see these tomorrow? What is the process for doing so?
Hamer, Douglas. “Claude Lorraine Glass.” Apollo, v. 63, no. 374, April 1956, pp. 130-131, ill.
Balthasar, Theodor. Micrometria: hoc est, de micrometrorum, tubis opticis, seu telescopiis & microscopiis applicandorum varia structura ac usu multiplici opusculum, cum observationibus
astronomicis, tum & aliarum rerum dimensionibus plurimum inserviens / Theodoro Balthasaris.
Christian-Erlangae: Sumpt. J.A. Lorberi, Typis D.M. Schmatz, 1710. 120 p.,  plates (some folded)
Berlye, Milton K. The Encyclopedia of Working with Glass. New York: Everest House, 1983, 1968. "Mirror Making": pp. 239-246. TP859 .B55 1983
Husson, Francois. Artisans francais: Les Miroitiers, etude historique. Paris, 1904. 266 p. Primarily mirror making in France. Bibliography, p. 255-260, geared to 19th century French publications.