TRAVELS^ IN BftAZIL. 



293 



From what is called the black gold formation, in which 

 arsenical pyrites, and iron-stone containing manganese 

 occur, we received, besides other forms of gold, also 

 small crystals in cubes. But the most beautiful form of 

 gold is that in iron mica-slate, particularly in the large- 

 foliated, generally undulated -curved, in which pieces weigh- 

 ing several ounces are often found. It cannot but be ob- 

 served, that in Brazil the gold occurs in such abundance 

 with iron-mica, whereas, for example, at Fichtelberg, in 

 Bavaria, where iron-mica is frequent in quartz, no trace is 

 to be found of it. But in general the crystallisations of 

 gold seem to be more frequent in the primitive than in the 

 flotz mountains (we have not had an opportunity of ob- 

 serving the transition formation). 



Note 3. 



The kyanite and rhaeticite of the Serra do Cara9a is 

 generally bluish grey, passing into light azure, but seldom 

 pure, mostly dirty. We found some beautiful rhae- 

 ticite in the Morro de Villa Rica, where however it did 

 not appear in veins, but only in solid pieces of compact 

 quartz. It has there a silver and milk-white colour, 

 passing into peach-blossom, a decided mother of pearl 

 lustre, and is long- narrow- and rather curved-radiated. 

 The common shorl, of which we found casual pieces on 

 this mountain, appears in small, middling-sized crystals, 

 growing close to and over one another, and therefore in- 

 distinct. As the superficies of these casual pieces is covered 

 with a red clay, we conclude that it belongs to the formation 

 of the tapanho-acanga. Mr. Von Eschwege mentions also 

 an auriferous shorl rock between his iron mica-slate and 

 the quartz-slate. 



u 3 



