NO. 1148. TOPAZ CB YSTA LS IN THE NA TIONAL MUSE UM—EA KLE. 



365 



/« 



m 



characterized by a broad development of the brachydome / and a 

 narrow base and prominent n faces. Fig. 10 shows a common combi- 

 nation. (No. 47119, U.S.N.M.) 



Besides these few crystals in the systematic mineral series there are 

 a number of others kept intact in a set of Japanese 

 minerals and rocks, which was presented by that 

 Government to the Museum at the close of the Co- 

 lumbian Exposition. They come from the two local- 

 ities, Otaniyama, Omi province, and ISTakatsugawa, 

 Mino province. The first-named locality is repre 

 sented by two good crystals, one of them an excep- 

 tionally large square prism, measuring 5 cm. across 

 its prismatic face. The combination is of I, c, m, and 

 /. The prism m is narrow and / small in propor 

 tion to the size of crystal, while the broad base caps 

 the prisms without any inter- 

 vening pyramid faces. The 

 smaller crystal has no base, 

 making the / faces large in consequence, 

 macrodome d is also prominent. 



The Mino province is represented by a lot of 

 small crystals, all of which are characterized by 

 a broad development of the domes / and d and 

 little or no base. The other common forms, ?/, o, 

 ?(, i, and h, are present. 



BRAZIL. 



KiG. 11.— Topaz cri 



TAL FROM BKA/.II, 



in 



I s 



The 



Fl(i. 12.— Toi'AZCJtVSTALFROM 



Brazil. 



m 



m 



The well-known Brazilian topaz crystals, al 

 though perhaps inferior to 

 the liussian in size and 

 beauty, seem to excel them 

 in the number of rare forms and combinations. 

 The collection exhibits from the Allla llica district 

 a fine lot of wine-colored well-formed individuals, 

 as well as several of the common deep-yellow, long 

 prismatic ones. 



Two general types are apparent. The first is 

 characterized by long striated prismatic faces, 

 capped usually by a low pyramid. The sec- 

 ond has a steeper habit, due to the predominat 

 ing pyramid o )221| and dome y |041| as termi- 

 nations. 



The crystals of this type are of the uniform 

 wine color and have a richer and more perfect development of forms 

 than those of the first type. 

 Fig. 11 shows one of the simplest combinations of the first type. It 



Fig. 13.— Topaz crystal 

 fro.m Brazil. 



