THE IRON ORES. 3881 
Kidney ores are mined at the present time in the seven following 
counties, viz. : 
Columbiana, Jackson, 
Stark, Gallia, 
Tuscarawas, : Lawrence. 
Vinton, 
Those of the first three counties are derived from the Kittanning 
and Clarion horizons mainly ; those of Vinton and Jackson from the 
Clarion and Putnam Hill horizons, and those of Gallia and Lawrence 
come from the Kittanning and Freeport horizons. Mahoning county 
formerly produced a small quantity of Kidney ore from the horizon of 
the Sharon shales. 
Block ores are now mined in the eleven counties herewith named: 
Mahoning, Hocking, 
Stark, | Vinton, 
Tuscarawas, Jackson, 
Muskingum, Scioto, 
‘ Licking, Lawrence. 
Perry, 
In Mahoning and Stark, the production is very feeble, or has 
altogether ceased. It was based on the ores borne by the two Mercer 
and the Putnam Hill limestones, respectively. Tuscarawas, Muskingum 
and Licking rely on the same sources. The Putnam Hill horizon 
does not furnish a block ore beyond the last-named limit. Perry and 
Hocking counties mine only the Lower Mercer block ores ; Vinton, Jack- 
son and Scioto depend on the three Mercer horizons, to which Jackson 
adds a trifling amount of. block ore from the sub-carboniferous horizon. 
Lawrence makes use of a considerable quantity from the Mercer 
horizons. 
The limestone ore is mined on a large scale in the first four coun- 
ties named below. In the last two the production is less important : 
Lawrence, Vinton, 
Gallia, Hocking, 
. Jackson, Perry. 
From these statements it will be seen that iron ore is now mined 
in 15 counties of Ohio at the 12 distinct horizons named above. 
