58 
of Colombia. These are from “El Dorado” from which came 
the first important yield of gold in the New World. 
Case 7, Front. — Gold ores, Great Britain. Tbe collection 
from the New Morgan Mine, Dolgelly, Wales, is worthy of special 
attention both on account of its completeness and on account of the 
character of the ore. The gold is nearly all free, and much of it 
is visible to the eye. Specimens of ore from various parts of the 
mine are shown, also specimens of the country rock. 
Case B. — Collection of nearly all the known alloys of gold 
and silver with copper, tin, zinc, lead, arsenic and other metals. 
Collection illustrating methods of saving gold and silver practiced 
by Messrs. Tiffany & Co., New York. Here are shown wash 
water, concentrates from an exhaust blower that collects the dust 
of the shops, pieces of flooring of the shops, and shoes worn by 
workmen, and beside each of these are placed buttons of gold and 
silver obtained from articles of size similar to those shown. 
Cases C and D. Large specimens of gold ores, Colorado. 
SILVER. 
Case 8. Front. — Type specimens of silver-bearing minerals. 
These are, in the order of their richness: native y or wire silver ; 
argentite, 87 per cent, silver; cerargyrite, 75 per cent, silver; 
pyrargyritey 65 per cent, silver; proustitey 65 per cent, silver; 
stephanitey 68 per cent, silver. Galena and cerussite may also be 
regarded as ores of silver, for, though they contain but small per- 
centages of silver, they are so abundant as to constitute very im- 
portant ores. With these should be mentioned, Tetrahedritey 
which may contain as high as 17 per cent, of silver. There are a 
number of rarer silver-bearing minerals. 
Case 8, Rear. — Silver ores, Utah. 
The specimens from Utah illustrate an unusual occurrence. 
They are from the Silver Reef, and consist of sandstone impreg- 
nated with argentite and cerargyrite. In one specimen these 
minerals may be seen replacing organic remains. 
Case E. — Large specimens of silver ores, Colorado. 
Cases 9 and 10. — Silver ores, Mexico. 
This collection includes examples of both the ores and the 
rocks in which they occur of the important mining districts in 
Northern Mexico. 
