516 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



sometimes of considerable size, the one weighing 40 hundredweights, mentioned above, 

 having been found in Brazil. 



The principal locality for agate, carnelian, and other varieties of chalcedony is a 

 mountain chain consisting mainly of decomposed melaphyre, which is about 400 miles in 

 length and extends from Porto Alegre, in Rio Grande do Sul, in the east to the district of 

 Salto on the Uruguay river, in Uruguay, in the west. Cutting through this chain in the 

 north are the Rio Pardo and Taquaire, flowing into the Gulf of Alegre, and in the valleys 

 and beds of these rivers carnelian is found, while in the heights above striped agate is more 

 common. From the Campo de Maia, fifty miles south of the Rio Pardo, come sardonyxes 

 weighing as much as a hundredweight and often of magnificent colour. In the tributaries 

 of the Uruguay, in the districts of Tres Cruces and Meta Perro, bluish agate as well as the 

 striped variety is found. 



For a long time this locality was the only place from whence bluish-grey agate was 

 obtained. Though dingy and unattractive in themselves they possess two distinct 

 advantages over the coloured agates of Oberstein. In the first place, they are easily 

 coloured artificially ; and in the second place, the layers of which they are built up are 

 perfectly straight, which is a great assistance to the lapidary in the cutting of onyxes. 

 Natural stones of a black colour are very rare ; among several thousand hundredweights of 

 material there will perhaps be scarcely a single black specimen. Layers of a fine 

 emerald-green colour are also very rare ; when they do occur, they are always situated 

 immediately under the amethyst which rests on the agate. Rose-red agate is uncommon, 

 but the deep flesh-red colour of carnelian is rather frequent in Brazilian agates. 



The occurrence of agate and the quartz minei-als with which it is associated in Brazil 

 was discovered in 1827 by a native of Oberstein. These stores of mineral wealth, which up 

 till that time had been lying idle, were then collected from the surface and from the loose 

 clayey gi'ound and were sent in great amount to Oberstein, these minerals soon becoming 

 important articles of export. In spite of the abundance of material its collection is not 

 very easy, for the localities are situated for the most part in inaccessible regions, and the 

 task of transporting the stones to the coast is extremely arduous. In spite of these 

 difficulties, however, large quantities are sent every year to Oberstein, where but little 

 agate from other localities is now cut. 



In order to give an idea of the importance of this export, and incidentally of the 

 agate-cutting industry, the following figures representing the weight of agate, including 

 carnelian and other varieties of chalcedony, obtained from Rio Grande do Sul alone are 



Cwts. 

 1872-3 3100 



1873-4 3850 



1874-5 1200 



1875-6 1900 



1876-7 1720 



Cwts. 

 1877-8 1825 



1878-9 1530 



1879-80 1950 



1880-1 380 



1881-2 700 



It will be seen that the output varies a good deal ; the price of rough material is 

 also subject to fluctuation, varying between 5000 and 10,000 reis per arroba (£2 to ^4 per 

 hundredweight). For exceptional material as much as 100,000 to 200,000 reis per arroba 

 may be paid. There are no cutting works in Brazil itself; an attempt to establish such 

 was once made by a few emigrants from Oberstein, but was unsuccessful ; articles of cut 

 agate, therefore, have to be imported from Oberstein. 



In India the mother-rocks of agate and the other varieties of chalcedony, already 



