56 



BULLETIN 118, UNITED STATES NATIONAL MUSEUM. 



morphism. Demantoid occurs in serpentine. The chrome garnets 

 belong particularly to serpentine; found also in granular limestone. 



The mineral is widely used as a semiprecious stone, although the 

 color is in some cases so deep that it is not much in favor. The most 

 noted garnet region of the world is that some 60 kilometers north of 

 Prague in Bohemia. For many years this has been almost the only 

 commercial source of the common ruby garnet found mounted in 

 various and multiple forms in the jewelers' shops. 



Of late years a great many very beautiful garnets have been brought 

 in from the Indian Reservations in Arizona and New Mexico, where 

 they are gathered from the loose sands and gravels which result from 



1 .JT- 



Fig. 6.— Garnets in matrix. 



a decomposition of boulders of garnetiferous gneiss which, according 

 to Gregory, 1 have been brought from an unknown depth to the sur- 

 face by igneous injections. These are often of no mean quality and 

 are popularly spoken of as Arizona rubies. The principal localities 

 are the Mule Ear and Moses Rock fields in southern Utah and the 

 Garnet Ridge field in the adjoining portion of Arizona. 



LIST OF SPECIMENS. 



GARNET, variety ALMANDITE. 



BOHEMIA. 



Cabochon, irregular elliptical girdle; violet-red; 24.42 carats; 25 by 13 by 6 

 mm. Isaac Lea collection No. 969 



Cabochon, elliptical girdle; violet-red; 23.2 carats; 24 by 13 by 7 mm. Isaac 



Lea collection No. 968 



' Economic Geology, vol. 11, 1916, p. 224. 



