70 
LEAD ORES, 
Cases 15, 16, 17, 18, 19, and 20. 
Galena— sulphide of lead— of all the lead minerals is most 
abundant and constitutes the fundamental lead ore. When pure 
It contains 86.6 per cent. lead. Galena without exception contains 
more or less silver, and where the amount of silver is present to 
make its extraction profitable, it is called argentiferous (silver- 
bearing galena). Handsome large crystals are found where Ga- 
lena occurs in a comparatively pure state. The crystals have 
cubical cleavage, and their faces, when unpolished, as well as the 
cleavage surface have a bright metallic luster. 
Cerussite — carbonate of lead — containing 77 per cent, of lead, 
usually white when pure, and Anglesite (lead sulphate) containing 
about 68 per cent., also of a white color when pure, are the next 
most important lead minerals. 
This metal is used for lining sulphuric acid chambers, pipes 
for conveying water and gas, and the manufacture of alloys, lead 
paints, etc. 
Case I. — Lead ores. 
Case J. — Alloys of lead with other metals. 
SPECIAL FEATURES. 
Exhibits in the center of the hall : 
Object K. — Block of ore from 40 ft. level of the Mitchell, 
New South Wales. 36 tons yielding 3,406 oz. silver, and gold at 
the rate of $15 per ton. 
Object L. — Auriferous Pyrite, Park County, Colo. Assays 
$45 gold per ton. 
Objet M . — Silver and gold ore from the State of Washing- 
ton, and other specimens from American localities. 
Object ]ST . — Auriferous quartz. San Miguel County, Colorado. 
Assays average $6 to $S gold per ton. 
Object O. — Copper-silver ore. Ouray County, Colorado. 
Assays copper, 28 per cent.; silver, 42 oz.per ton. 
Object P. — Silver-lead ores. Barrier Range, New South 
