specular stone

English

Noun

specular stone (countable and uncountable, plural specular stones)

1. (historical) A type of transparent stone (lapides speculares) that was used in classical times for glazing, adding sparkle to floor coverings, etc. Various modern authors have identified this stone as selenite, talc, or mica.
   • 1715, Guido Panciroli, Henricus Salmuth, The History of Many Memorable Things Lost, which Were in Use Among the Ancients:

     Specular Stones were a shining kind of Substance, and (according to Basil ) transparent like the Air.

   • 1859, Nathaniel Fish Moore, Ancient Mineralogy, page 166:

     One use of mica or of selenite that especially merits notice is mentioned by Pliny, when, speaking of the material of which bee-hives should be formed, he says many had made them of the specular stone, that they might see the bees at work within.

   • 1883, Sextus Propertius, Aristaenetus, Walter Keating Kelly, The Elegies of Propertius: The Satyricon of Petronius, page 267:

     The servants removed all the first tables, brought in others, then strewed the floor with saw-dust tinged with crocus and vermilion, and (what I had never seen before) with specular stone beaten to powder.

   • 1956, John Donne, “The undertaking”, in The Songs and Sonets of John Donne:

     It were but madnes now t'impart The skill of specular stone, When he which can have learn'd the art To cut it, can finde none.

   • 2013, André Authier, Pliny the Elder and 'Natural History' (Naturalis Historia), 77 AD:

     He also mentions the property of cleavage of the specular stone (lapis specularis): 'The specular stone, which deserves also to be called a stone, is sectile (sectilis) and can be cut into slices as thin as can be desired....

2. Any transparent or translucent stone.
   • 1845, The United States Catholic Magazine and Monthly Review:

     They were furnished with wooden sashes in which were placed transparent or specular stones. These were of various kinds:

   • 1859, Nathaniel Fish Moore, Ancient Mineralogy, page 166:

     The glass (ϋαλοϛ), in coffins of which Herodotus (iii., 24) says the Ethiopians called μακροϐίοι inclosed their dead, which was dug among them in great abundance and easily worked, was, of course, one or other of these specular stones.

   • 2014, Albert Russell Ascoli, Early Days of X-ray Crystallography, page 177:

     Specular stones were minerals such as selenite (gypsum) or micas that could be cut into thin and transparent sheets, which Roman craftsmen used to seal windows with or in greenhouses.