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stone, mexico, blue and green

TURQUOIS, ter-koiz', a mineral whose name (often spelled "turquoise))) alludes to its coming into the European market through Turkey. It is a hydrous phosphate of alum inum, containing a small amount of copper, to which its color is due. It has been a favorite gem in the Orient, from the earliest times, ap pearing in Egyptian jewelry of extreme an tiquity. Turquois does not crystallize, but forms little veins and nodules in a trachytic igneous rock. Its hardness is 6, its specific gravity from 2.6 to 2.8, lustre somewhat waxy and its color varies from dull green to beautiful pale blue. In modern jewelry, only the fine '

cases, traditions still linger among the Indians, and the stone is held sacred to Montezuma and his people. It figures largely in the Spanish records of the conquest of Mexico, and was in part the highly prized achakhihuitP) of the Mexicans; though in central and southern Mexico this stone was not turquois but green The chief locality is near Los Cerillos, ew Mexico; it is also mined at several other points in New Mexico, Arizona, Nevada and California. A substance often used in place of true turquois is the so-called bone-turquois or ondontolite, which is fossil bone colored blue by phosphate of iron. It is easily distinguished un der the microscope by its structure, and by its not yielding a blue color with hydrochloric acid and ammonia. Turquois in the natural rock has recently been very extensively cut into gem stone and sold under the name of uturquois matrix?) Consult Pogue, J. E., 'The Turquoise; Its History, Mineralogy, Geology, etc.) (206 pages plates Memoirs National Academy of Science, Vol. XII, pt. 2).