A phosphate gemstone, sky blue to pale green, which forms as veins and nodules in the fissures of sandstone and trachyte. It was mined by the Egyptians from the late Predynastic period onwards and was almost as highly prized as jade in Mesoamerica. It was also highly prized for jewelry in western Asia and the American Southwest. Turquoise was obtained from the Sinai Peninsula before the 4th millennium BC in one of the world's first important hard-rock mining operations. It was transported to Europe through Turkey, probably accounting for its name, which is French for Turkish.