72 MINERALS OF CHILE. 



The results I obtained are as follows: 



1 2 



Iodine 52.834 53.109 



Silver 46.521 46.380 



Chlorine trace. trace. 



Copper trace. trace. 



99.455 99.489 



The formula Ag. I gives as percentage — 



Iodine 53.85 



Silver 46.15 



100.00 

 ARQUERITE. 



This mineral is found in great abundance at the mines of 

 Arqueros, near Coquimbo ; in fact it is the ore of those mines. 

 It is quite like native silver in appearance, with, however, a 

 little more greasy luster. It is disseminated through a calca- 

 reous rock. Several specimens examined furnished different 

 proportions of silver and mercury, the proportions of silver 

 varying from eighty-three to ninety-two per cent. M. Do- 

 meyko, who has had opportunity of examining a greater 

 variety of specimens, gives the following fixed composition : 



Silver 86.49 



Mercury 13.51 



The formula is Ag. 6 Hg. 

 In all likelihood there is a definitely constituted silver amal- 

 gam at Arqueros, but in most instances is altered by admix- 

 ture with native silver. 



REMARKS ON THE GEOLOGY OF THE SILVER-ORES. 



In speaking of the copper and gold veins it was remarked 

 that they traversed the granite and other old unstratified rocks. 

 M. Domeyko thinks that he has established a law in the distri- 

 bution of the metalliferous veins of Chile. It is that gold and 

 copper veins, exempt from arsenic, antimony, and silver, abound 

 in the granite-rock ; while all the silver-veins, without refer- 

 ence to the associates of the silver, belong to the stratified 

 rocks ; and also that the copper-veins found in stratified rocks 

 are very frequently argentiferous. M. Crosnier, however, points 

 out two exceptions to this rule in the province of Copiapo, viz., 

 the Pampa Larga and Garin mines. The Pampa Larga veins 



