DEPARTMENT OF GEOLOGY 
63 
nite are examples of rarer oxidized ores of antimony, valen- 
tinite, etc. Ingot antimony and products of smelting stibnite 
are also shown. 
Arsenic ores shown here include the sulpharsenide of iron, 
leucopyrite. Much of the arsenic of commerce comes as a by- 
product from gold or other ores. One such by-product is the 
arsenical flue dust from treating the silver-lead ores of Laurium, 
Greece, in which distinct crystals of the oxide or “white arsenic” 
are plainly visible. 
Following the antimony and arsenic ores is a case of ores 
of nickel, cobalt, and aluminum. 
NICKEL, COBALT AND ALUMINUM. 
A series of specimens of nickel and cobalt -bearing minerals 
is arranged in the order of their richness. 
A collection of nickel and cobalt ores from the important 
deposits of these metals is shown. The most important ores 
are two: (i) the sulphide of iron, pyrrhotite, which, in some 
localities, carries minute inclusions of the sulphide of nickel, 
pentlandite; (2) the apple-green silicate garnierite. 
Nickel and cobalt ores fom Canada, New Caledonia, and 
Norway, which are the important producing countries, also 
nickel and cobalt ores from Oregon, Missouri, and other minor 
localities, are shown. In the floor case opposite are larger ex- 
amples of nickel ores and arsenic ores. This wall case also 
contains a series of minerals carrying aluminum in such form and 
quantity that it may be profitably extracted. These include 
the present universal aluminum ore, beauxite, and some min- 
erals from which aluminum may be smelted in the near future. 
TIN. 
Tin ores from South Dakota, New South Wales, Mexico, and 
Alaska, together with a nearly complete collection of the ores 
and rocks of the well-known tin mines of Cornwall, which have 
been worked from the beginning of history, are shown. 
The process of reduction of tin ores to metal is illustrated by 
specimens from the Redruth Smelting Company of Cornwall. 
Other examples of tin ore may be seen in the West Dome. 
Following the tin ore is a case of manganese ores. 
MANGANESE. 
A collection of minerals carrying manganese in commer- 
