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TIN. 
Case 11. — Tin ore from South Dakota. The tin is in the 
form of cassiteriie, a black oxide which can be seen scattered 
through the granite. This is the universal ore of tin, containing 
about 78 per cent, of the metal. Some specimens of stream tin 
are also shown. This is formed by disintegration of the rocks 
containing the ore, and removal of the lighter minerals by running 
water. The cassiterite being very heavy stays behind and is found 
in the bed of the stream. 
Case 12. — Tin ore from the famous Cornwall Mines of 
Great Britain, which have been in operation many centuries. 
Case 13. — Process of reduction of tin ores illustrated by 
specimens from the Redruth Smelting Co. 
ANTIMONY. 
Case 14:. — Specimens of stibnite^ the universal antimony ore, 
from various localities in Japan, California, New South Wales 
and Greece. That from the latter country bears an appreciable 
percentage of gold. Other specimens illustrate the alloys of anti- 
mony which are of use in the arts. 
MERCURY. 
Case 15. — A series of ores containing mercury and cinnabar 
and the rocks associated with them, from the New Almaden mines, 
California. Cinnabar is the red sulphide and the mineral from 
which mercury is chiefly obtained. Stages in the process of roast- 
ing the ore for extraction of the nietal are shown, and a chart near 
by illustrates the kind of furnaces used. Mercury ores from Spain 
and New Granada, S. A., are also shown. 
NICKEL. 
Cases G and H. — A complete series showing ores of nickel, 
processes of extraction and applications of the metal, presented 
by the American Nickel Works of Camden, N. J. Note as the 
