152 TRANSACTIONS OF THE [aPR. 21, 



crystals and cut euclase from Brazil and Siberia; and a number 

 •of interesting precious and ornamental stones. 



The Mexican exhibit was especially rich in its display of sil- 

 ver ores. Magnificent masses were covered with wire silver, and 

 some lumps of amalgam weighed twenty pounds each. There 

 were shown here splendid crystals of argentite, stephanite, pyr- 

 argyrite, also scalenohedral crystals of calcite, of the Iceland 

 spar variety, over six inches long and four inches in diameter, 

 covered with beautiful white crystals of stilbite, similar to that 

 from Iceland. Magnificent veined blocks of the so-called Mexi- 

 can onyx came from Tecali, in the State of Puebla, and a large 

 series of casts of Mexican meteorites, of many of which little is 

 known outside of Mexico. These casts were presented to the 

 Imperial Museum at Vienna. 



In the magnificent building of the Argentine Eepublic, the 

 National Department of Mines, of Buenos Ayres, Director-Gen- 

 eral H. D. Hoskold, had a collection of eighty flat cases 25x35 

 inches. Among the more important exhibits were the large 

 series of silver minerals from the Cerro Negro Mountains in the 

 province of Rioja, consisting almost entirely of native silver in 

 limestone, frequently associated with zinc-blende. The silver was 

 -either in wires, cubes, or veins, with cerargyrite and argentite. 

 A mineral was also exhibited under the name of argentarse- 

 nickel, claimed to be a new species, with the following analysis : 



Silver 32.22 



Zinc 6.60 



Nickel . . . . , 12.58 



Iron 8. 40 



Manganese ^ o 0, 70 



Arsenic 23. 46 



Sulphur 13.04 



Insoluble matter 2. 60 



Moisture 0.34 



99.94 



The ore of this district is exceedingly rich, and an assay gives 

 "8,771 ounces of silver to the English ton. Among some specimens 

 were also proustite and stephanite ; a large series of specimens, 

 exhibiting free silver and gold, from the province of Catamarca ; 

 from the province of Salta, a large series of copper minerals con- 

 taining ores of silver, lead, and antimony, notably some beauti- 

 ful crystals of stephanite. From the province of Cordoba were 

 some interesting marbles, one a beautiful concretion of rose- 

 €olored marble about eight inches in diameter ; from the pro- 

 vince of Salta large crystals of borax; and a case was filled by 



