64 
CASES 9 AND 10. — Lead ores. Type specimens of lead- 
bearing minerals. These are— 86 per cent, lead, the most 
abundant lead mineral and fundamental lead ore ; and the follow- 
ing minerals formed from it by oxidation: Cerussite, 77 per 
cent, lead, and anglesite, 68 per cent. lead. 
There are other minerals which contain lead, but they are 
not of sufficient abundance to be important as ores. The case 
contains also lead ores from Illinois, Wisconsin, and Missouri. 
These contain very little silver, and are mined for lead only. 
CASES 11 AND 12. — Silver-lead ores. In appearance these 
are similar to the silver-free lead ores of cases 9 and 10, from 
which they differ only in that the lead-bearing minerals also carry 
silver. 
HALL 79. 
FREDERICK J- V- SKIFF HALL 
ORES OF THE BASE METALS. 
The collections in this hall comprise ores of iron, copper, 
tin, zinc, nickel, manganese, mercury and antimony, together 
with various metals and metalloids of minor importance. The 
ores of each metal are grouped together. 
Under each group are placed type specimens of the differ- 
ent ores of the metal arranged in order of their richness. Each 
of these is accompanied by a group of the materials of which 
the specimen is composed, so arranged as to show plainly the 
composition of the specimen. With the type specimens and 
making up the bulk of the collection specimens of ore from 
different, localities are shown arranged in geographical order. 
Specimen labels show the mineral of the ore and the amount of 
metal contained, where this is known. It should be remembered 
that many of the ores produce more than one metal, in which 
case the specimen is placed in the group of the predominating 
metal. 
Entering the Hall from the West Dome, the visitor should 
keep to the left, following along the walls until the starting 
point is reached, when the large specimens along the center of 
the Hall may be examined. 
