TRAVELS IN BRAZIL. l65 



The latter, which is here called Massa branca, is 

 the surest indication of the presence of topazes, 

 which lie loose and scattered in it as well as 

 (though more rarely) among the broken and de- 

 composed quartz. The workmen give the name 

 of Malacacheta to the fine softened mica of a yel- 

 low and pinchbeck-brown earth, which one is 

 tempted to call earthy talc. Topazes are found in 

 it, but less frequently than in the broken remains 

 of veins ; and they have been observed, not only in 

 the softened parts of the formation, but, as for in- 

 stance at Capao, also in that which is still solid. 

 The vein of quartz, filled with porcelain earth, and 

 containing the topazes, commonly runs between 

 rifts of earthy talc, which is distinguished by its 

 colour and compactness from that lying near it, 

 and is called Forma9ao. The quartz vein, which, 

 on account of the mobility of the whole mass, does 

 not always preserve the same direction, but at the 

 time of our visit ran from north to south, is from 

 one inch to a foot and a half or more in thickness, 

 and is carefully followed by the workmen. It fre- 

 quently widens into large nest-like expansions, 

 which present nothing but sterile broken quartz 

 without topazes. The latter are also found, but 

 very seldom, combined with the quartz rock or 

 rock-crystal, in general broken at one extremity ; 

 we were never able to find, even in the mine, any 

 * with crystals terminated by planes at both extre- 

 mities. The topaz miners have a custom very un- 



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