Geography of Ohio 139 



IRON 



Three classes of iron ore have been worked for this mineral 

 in the state. The most conveniently^ handled of all perhaps was 

 that obtained from bogs, though a furnace for reducing this 

 kind of ore was not erected until 1824. Nearly all the bog ore 

 furnaces were built in the northern part of the state near the 

 shorelines of the ice-front lakes. The ore is thought to have been 

 deposited by spring water which combined chemically with cer- 

 tain organic products of bogs, making a precipitate of iron. This 

 source of iron never proved very profitable, consequently it was 

 not able to compete with other ores. 



In connection with certain clastic beds of the lower Pennsyl- 

 vania formations, man}' iron stone concretions occur. These 

 appear to be nodular clay products in which the iron has been 

 assembled; possibly the iron concentrates made the concretions. 

 Through the weathering of these horizons the matrix rock is 

 more easily disintegrated; the concretions endure, and are found 

 along slopes and stream courses. The earliest furnaces using 

 this ore gathered their supply chiefly from valley bottoms. The 

 supply being limited, these furnaces did not continue long in 

 operation. 



The most valuable iron ore that has been worked in Ohio is 

 a limonite, first found as pockets or depressions on the upper 

 surface of the Niagara limestone; sometimes many tons of ore 

 were removed from a single bod}'. The second blast furnace 

 built in the state, along Brush Creek, in Adams Count}-, used 

 these ores. Other furnaces were shortly put up in the same area. 

 Later they ceased to be profitable, because of the higher grade 

 ore found in the Hanging Rock region of Lawrence County. 

 This was also a limonite, but instead of occurring in pockets, it 

 existed as continuous beds at several horizons in the lower Penn- 

 sylvanian formations. The Hanging Rock limonite is a weathered 

 carbonate of iron. In weathering, the iron is hydrated by the 

 action of ground water or of the atmosphere. These beds bear 

 limonite for some distance below their outcrops, but blend grad- 

 ually into the unaltered carbonate ore. 



Early furnaces. The first blast furnace in this state was founded 

 in 1806 at Poland, in ]\Iahoning County, and commenced mak- 

 ing iron in 1808. This furnace used the nodular clay iron-stone 



