Turquoise

Turquoise (i.e. 'the Turkish stone;' spelt also turkis, as by Tennyson, and turqucis), an ornamental stone, essentially a phosphate of alumina, but containing also a little oxide of iron and oxide of copper. It is harder than felspar, but softer than quartz, and has a greenish-blue colour, and occurs as thin veins in slate rock. It is opaque, or sometimes translucent at the edges. The true oriental turquoise is found only near Nishapur in the Persian province of Khorassan. Old mines no longer worked are found in the Sinaitic peninsula; and of late Mexico produces good turquoises. A famous one, which once belonged to Nadir Shah, was two inches long, and was offered for sale at Moscow in the 18th century for £780. The name Callaite has been given to turquoise.—Fossil turquoise or odontolite is simply the fossil ivory of the Mammoth (q.v.), coloured blue by phosphate of iron, a blue which seldom fades. A mineral very like a greenish turquoise is found in Brittany, and has been named Variscite. It is sometimes called Oriental Turquoise; whilst the name Occidental Turquoise is given to a substance of similar colour, found near Simon, in Languedoc, which is said to be merely bone coloured with phosphate of iron.