DEPARTMENT OF GEOLOGY 
6i 
ern Michigan. In these ores the copper exists as nodules of 
free metal, which may be seen projecting from the enclosing 
rock matrix. With these are placed large specimens of Arizona 
ore of a similar nature. 
Returning to the wall cases the visitor may inspect next 
foreign copper ores contained in two cases. Those of Great 
Britain, chiefly from Cornwall and Wales, have been worked 
from the time of the Phoenicians. Those from Germany, 
which also represent mines of great antiquity, should be stud- 
ied in connection with zinc, silver, and lead ores from the same 
The six cases along the wall from the last of the copper ores 
to the entrance to Hall 63 contain the zinc ores, which will be 
encountered in a geographical order which is the reverse of 
that of the copper ores; that is, the foreign ores come first and 
the American after. Three immediately adjacent floor cases 
contain the larger and choicer specimens. With the zinc ores 
are placed the ores of the allied but little used metal, cadmium. 
The wall case nearest the copper ores contains foreign zinc 
ores, of which the most important represented in the collection 
are the English and Welsh, the Greek and the Spanish. The 
original “black jack” of the Welsh miners is here represented 
and may be profitably compared with the ordinary yellow and 
brown blendes, which are often miscalled black jack in this 
country. Immediately in front of this case are two floor cases, 
one of German zinc-lead ores, which should be studied in connec- 
tion with the German ores of other metals, shown elsewhere. 
The other floor case contains choice examples of the zinc ores of 
Laurium, Greece, which have long been famous for their varieties 
of color and richness of lustre, making them very attractive to 
the eye. They are chiefly the carbonate, smithsonite. 
Additional Spanish zinc ores occupy the bay of another wall 
case, the upper part of which contains the zinc ores of Arkansas. 
The great purity and richness of the Amercian zinc ores, as 
compared with the foreign, is at once apparent, even on casual 
inspection, and this high quality will be noted in all the suc- 
ceeding cases which contain American ores. In this case there 
is a collection of the final, intermediate, and by-products of the 
smelting of zinc ores as carried out at La Salle, Illinois. Follow- 
ing the Arkansas ores are two cases of zinc ores from Missouri, 
