chalcedony

Etymology

Borrowed from Latin chalcēdōnius, probably derived from the name of the town Chalcedon in Asia Minor.

noun

1. A form of fine-grained quartz that is nearly transparent or has a milky translucence; it fractures conchoidally.
   Although there are dozens of different types of gems, among the best known and most important are […] . (Common gem materials not addressed in this article include amber, amethyst, chalcedony, garnet, lazurite, malachite, opals, peridot, rhodonite, spinel, tourmaline, turquoise and zircon.) 2012-03, Lee A. Groat, “Gemstones”, in American Scientist, volume 100, number 2, archived from the original on 2012-06-14, page 128