64 FIELD MUSEUM OE NATURAL HISTORY 
cially available quantities, is shown, also ores of manganese 
from many important mining districts. Especially to be noted 
are the ores from Santiago de Cuba, which are typical, and those 
from Xew Jersey, which are unique in mineralogical character. 
Polished specimens of rhodonite from England, illustrate an 
occurrence utilized both as manganese ore and for ornament. 
In the two adjacent floor cases are large specimens of man- 
ganese ores. 
IRON. 
Iron ores fill six wall cases and two floor cases. 
The case following the manganese ores contains iron ores 
of South America and Mexico. A full collection of iron ores and 
surrounding rocks of the Cerro Mercado or Iron Mountain, of 
Durango, Mexico, shown here, illustrates a valuable occurrence 
of an important but little understood type of iron-ore deposit. 
Large specimens of a specular hematite from the state of Minas 
Geraes, Brazil, in the lower portion of the case, illustrate a 
micaceous hematite of world -wide distribution. Many of the ores 
in this case are from deposits almost unknown to the world at large. 
Foreign Iron Ores. — The most instructive specimens in this 
case are a complete collection of the ores and surrounding rocks 
from two iron ore deposits of eastern Russia. Better known 
ores represented here are those from England and Sweden. 
Conspicuous among the English ores here illustrated are the 
ochres, which are mixtures of limonite or hematite with clay; 
the soft, bright red hematites which occur in limestone, and the 
compact, spathic ore of the coal measures. German ores show 
more fibrous hematites and limonites and the well crystallized 
“sparry” siderite. 
Domestic Iron Ores. — Following the foreign ores are three 
cases of iron ore from the Lake Superior region. The ores in 
these three cases are from the most important iron ore mines of 
the world. It is to the proximity of these remarkably rich and 
pure ores that Chicago owes its present importance in the iron 
and steel industry. The ores are arranged in the cases under the 
several “ranges” as the iron mining districts around Lake Supe- 
rior are termed. While similar in many respects, differences 
between the ores of the several ranges may be noted even in the 
small specimens here shown. Specimens of a local magnetic 
iron sand are worthy of attention as coming from the im- 
mediate vicinity of Chicago. 
