Laz"u*li (?), n. [F. & NL. lapis lazuli, LL. lazulus, lazurius, lazur from the same Oriental source as E. azure. See Azure.] (Min.) A mineral of a fine azure-blue color, usually in small rounded masses. It is essentially a silicate of alumina, lime, and soda, with some sodium sulphide, is often marked by yellow spots or veins of sulphide of iron, and is much valued for ornamental work. Called also lapis lazuli, and Armenian stone.