432 GEOLOGY OF OHIO. 
report 7 to 8 per cent. of phosphates, almost enough to give it value as 
a fertilizer. It has been worked only on the lands of Hamden and 
Pine Grove Furnaces. On the former tract it ranged from 2 to 4 feet 
in thickness. Its appearance was good, and quite a large amount was 
mined before the real character of the deposit was discovered. Pine 
Grove Furnace had quite a similar experience. Within the last few 
years the ore was found on the furnace lands. It had fair thickness, 
and its general appearance was excellent, but in the furnace it proved 
mischievous to a high degree. The percentage of phosphorus probably 
exceeds that of the ore as found at Hamden Furnace. 
The place of this ore in the scale can be easily remembered. It 
lies directly above the Lower Kittanning coal (No. 5), or at the very 
base of the Kittanning shales.‘ This is also the position of the blue 
block ore of Tuscarawas county, but the horizon is not worked in the 
State, except at these three points. The so-called blackband of Holmes 
county belongs at this horizon. A heavy deposit of ore on the Cherry 
farm, in the southern part of Starr township, Hocking county, is 
perhaps referable to it also. 
Black Kidney Ore. 
The kidney ore that lies next higher in the series has various names 
in the several parts of the field. It belongs a few feet below the Middle 
Kittanning (or No. 6) coal, and from 50 to 55 feet above the Ferriferous 
limestone. This horizon is as persistent as any ore horizon of the 
Lower Coal Measures. It has now been traced continuously from the 
Pennsylvania line to the Ohio River. In the Hanging Rock district 
it is known by two names, viz., black kidney and red kidney. In the 
Hocking Valley it is the Snow Fork kidney. In Tuscarawas county it 
is “Shell ore,” and in Columbiana county it is known simply as kidney 
ore. There is, in fact, no part of the field where the shales that inter- 
vene between the Kittanning coals do not carry a notable quantity of 
iron ore. 
A little ore is taken from this seam in the Hanging Rock district 
on several furnace tracts. Across the river, in Kentucky, it is mined 
quite largely, where it is generally known as the Red kidney. The ore 
occurs in fairly regular concretions of moderate size. When the 
weathered ore is broken, black seams are often found traversing it, and 
from this fact one of its common designations is borrowed. It is well 
