374 GEOLOGY OF OHIO. 
The Barren Measures contain a notable quantity of iron, as the 
red color of the heavy beds of shale that form so conspicuous a part of 
them indicates, but the same fact points to the diffusion of the iron in 
a valueless form. The same general statement can be made for the 
Upper Coal Measures. There is occasional concentration of ore in 
connection with limestone and clay deposits throughout the series. 
When the Cambridge limestone, for example, is worked for furnace 
flux, a thin plate of good ore is often found to cover it, but the ore is 
never sought by itself. In some cases there is a blending of ore with 
the earthy limestones of the Freeport or Brush Creek type, which forms 
beds of several feet in thickness, and which has good weight, but which 
generally runs so low in iron, and so high in silica as to be without 
value. They seldom reach 30 per cent. of metallic iron. Many attempts 
have been made to mine and work these ores, which occur in several 
_ distinct and fairly persistent horizons. One of these deposits will be 
treated briefly on a subsequent page. 
In one case, at least, a charcoal furnace was built in Southern Ohio 
that was to rely upon one of these voluminous Barren Measure ores, 
but the life of the furnace was brief. After a single blast of short 
duration, the furnace passed into one of the “ picturesque ruins” to 
which so many of the charcoal iron furnaces of the Appalachian field 
have heretofore been doomed to come. One ore of a different char- 
acter that belongs to both the Barren Measures and the Upper Coal 
Measures deserves to be mentioned here. In the red clays that lie 
near or that sometimes replace the limestones of these series, nuggets 
of red hematite of high grade are often found. They range in size 
from pellets up to masses weighing 50 or 75 pounds. Being of high 
specific gravity and insoluble, they accumulate in the water-courses and 
on weathered outerops, and thus suggest a greater abundance of ore 
than there really is. In only one district of Ohio have they been 
found gathered into anything like a seam that would justify mining. 
In one or two townships of Noble county, at a horizon about 150 feet 
above the Barnesville coal seam (No. 8c) there is a good promise of | 
deposits that could be worked with profit if transportation were avail- 
able. The clay that holds the ore is but a few feet in thickness, and 
the aggregate of the ore makes a respectable part of the entire thick- 
ness. | 
In most cases, it would require the sifting of many feet of clay or 
