114 BULLETIN 118, UNITED STATES NATIONAL MUSEUM. 



as a precious stone, particularly when worn as a necklace and next 

 to the skin. Its opaque nature and robin's-egg blue color are its 

 most pronounced characteristics, but it can be determined absolutely 

 only by chemical tests. The only natural stone with which it is 

 likely to become confused is variscite, likewise an aluminum phos- 

 phate. From this last it can, as a rule, be distinguished by its blue 

 cast, variscite being green, inclined to yellowish. The mineral occurs 

 as a secondary product in veins and pockets 

 in aluminous rocks, both igneous and sedimen- 

 tary. It is easily and abundantly imitated 

 artificially, and on this and other accounts the 

 | 4&- so-called "matrix" turquoise — that is, stones 



including portions of the matrix— are most 

 jgf.% desirable. Turquoise is usually cut cabochon be- 

 cause of its opaque nature, and has been for cen- 

 turies much admired as a gem, both by -civilized 

 and barbarous people. In the United States it is 



Fig. 13.— Chinese carving i i • » ■ -vr i i twt u 



in tukquoise. found only in Arizona, iNevada, and JNew Mexico. 



LIST OF SPECIMENS. 

 CHINA. 



Carving, representing man and dragon; blue-green; 71.075 carats; 34 by 33 

 mm. (fig. 13) No. 1093 



FRANCE. 



Five fossil bone turquoise, cabochon, elliptical girdle; three green-blue, 

 two blue-green; total weight, 5.8 carats; 17 by 11 by 3 to 9 by 7 by 2 mm. . No. 591 



PERSIA. 



Two stones, cabochon, circular girdle; blue with brown matrix; 13.67 and 



12.55carats; 19by 5.5andl8by 6mm. Isaac Lea collection (fig. 13, pi. 12). No. 1812 



UNITED STATES. 



Arizona. 

 Mineral Park, Mohave County: 



Rectangular fragment polished; veinlet of blue in light brown matrix; 



9.045 carats; 15 by 12 by 5 mm. Isaac Lea collection No. 1097 



Cabochon, circular girdle; cobweb matrix, pale blue, green, and brown; 

 5.99 carats; 15 by 4 mm No. 1088 



Nevada. 

 Belmont, Nye County: 



Cabochon, elliptical girdle; blue in dark brown matrix; 9.315 carats; 24 



by 10 by 6 mm No. 1098 



Near Millers, Nye County: 



Polished piece; dark and light blue and green in brown matrix; 14.465 



carats; 25 by 15 by 5 mm. Isaac Lea collection (fig. 14, pi. 12) No. 109<> 



Tabular, keystone girdle ; mottled pale and dark blue with white matrix ; 



10.93 carats; 19 by 21 by 3 mm No. 1092 



Cabochon, elliptical girdle; pale blue with brown and green matrix; 



10.89 carats; 23 by 17 by 4 mm. (fig. 10, pi. 12) No. 1090 



Cabochon, elliptical girdle; blue with matrix of green and brown: 9.6 



carats; 30 by 10 by 4 mm. No. 1091 



Cabochon, elliptical girdle; dark and light blue and brown matrix; 



5.39 carats; 14 by 10 by 6 mm No. 1089 



