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UNITED STATES, CANADA AND MEXICO
301
ico to imitate the ancient objects, to meet the demand of visitors to that country. This material is entirely stalagmatic in its for­mation, and yellow-brown and red oxides of iron have been de­posited between the layers. It is generally cut across the layers, which gives it a beautiful veined appearance. When it is cut in the same direction as the deposition, the botryoidal structure is well shown, the mineral being so translucent that the markings resemble colored clouds. It is one of the most beautiful orna­mental stones of any age, and has been used extensively for or­namental purposes in Europe as well as in the United States, where it was first introduced about 1876, when it brought about ten times its present price. The natives in the vicinity of Pueblo sell large quantities of this material, made into trays, crucifixes, reliquaries, inkstands, penholders, paper-folders, and paper­weights, in the form of single fruits or bunches of fruit, fish, or other natural objects, which are copied, not only with regard to form, but often with remarkable skill in the utilization of the col­ors in the stone. So great is the variety of tints of color in which the material is found that there is scarcely a limit to its possibilities for such purposes. Bernardino de Sahagun refers to iztac chalchihuitl, white or fine green, and quite transparent, obtained from quarries in the vicinity of Tecalco, which Dr. Daniel G. Brinton ' believes to be the modern Tecali; and the de­scription and locality answer so well to those of our so-called Mexican onyx that there can scarcely be a doubt that this was referred to by Sahagun as iztac chalchihuitl.
In the summer of 1888, William Cooper, of Esperanza, discovered in the volcano of Zempoaetepetl, in southern Mex­ico, a deposit of a beautiful mineral, which has received the trade name of mosaic agate; this is really the so-called Mexican onyx. It is an aragonite, with the difference, however, that the latter is always veined or stratified, whereas the new material is a brecciated or "ruin aragonite." The original formation has evidently been entirely broken up, the fragments having been cemented together and the crevices all filled in with a new depo­sition of aragonite, showing conclusively that a deposit of Mexi­can onyx had been fractured by some disturbance, possibly vol-
1 Science, Vol. 12, p. 168, Oct. 5, 1888.