466 GEOLOGY OF OHIO. 
easily producing 3 tons per day. When mined, the ore is usually cal- 
cined on the spot in heaps, and the burnt ore then transported to the 
smelting furnaces. In building the piles, the ore is placed on its 
edge, so as to facilitate the operation. Considerable quantities of fuel 
have been heretofore mixed with the ore in the heaps, though it seems 
that there is sufficient carbonaceous matter in the blackband itself to 
produce the calcination when once the combustion has been started. 
The fuel that has been used for this purpose is the underlying coal No. 
7, which contains considerable sulphur, and hence is disadvantageous, 
as it contaminates the ore with the ash and increases the amount of 
foreign matter. The fact of the coal thus adding impurities to the 
ore, which affect the quality of the iron, is becoming understood, 
and less is now being used, though any fuel beyond the amount 
required to start the pile seems hardly necessary. ‘The ore is so 
easily reducible and fusible, that notwithstanding the care which 
may be taken in calcining it, large masses become cemented to- 
gether in the hottest parts of the pile, and if the heat has been too 
high, these masses or “loups” are so hard as to require severe labor to 
remove and break them up. In calcining, the ore loses considerable 
as fine dust, which is separated by screening, but it becomes enriched 
by the expulsion of the volatile matter from an ore of 25 per cent. to 
one containing 50 per cent. of metallic iron. At the Massillon and 
Dover furnaces there are consumed about 2 tons to 24 tons of ore to 
make a ton of pig-iron. The value of this ore, of course, varies, 
owing to different circumstances, but in 1879-80 it was worth in the 
neighborhood of $2.50 to $2.75 at the furnaces. Beside the blackband ore 
some little “‘ Mountain ore,” the calcareous ore overlying the blackband 
in places, is used, but the quantity is not large. It is of but local im- 
portance, and has been obtained chiefly in the eastern part of Tuscara- 
was county, in Fairfieldtownship. The ore is subjected to calcination in 
heap, as is usually done with ores of its class. As an ore it is highly 
valued. Nodular clay ironstone, “kidney” or “shell” ore is obtained 
in some quantity, but the supply is derived from surface pickings from 
the accumulation in the valleys and runs, where they have been weath- 
ered and accumulated from the shales which bear them. 
Horizons specially rich in these ores in the Coal Measures have 
already been referred to, as the shales over Coal No. 5, the Mineral 
Point or Newberry seam at Mineral Point and other places in Tus- 
