92 ANNUAL REPORT 
plied from an opening in the Putnam Hill limestone, which is there 8 
feet in thickness. The following is the composition of the stone: 
Per Cent. 
SULT as ee nd sate) Gat ah carte oe ote eA ce Upett eoiay AP enc Pt eR TE AL ND 
PAN UDUGOUD (he HeRamOr iN aT AUP MNe Net OA ay MY Se Paes Neen SUR LC Beers Ati tase 1.86 
FOrricrO Ried een Cae alec een spe ea RE eRe A a Cain 1.20 
Carbonatevot calenamit ge. sees rl eles rier eee a aan nN 91.16 
Carbonatelofmagnesiumems es wee ee eee 1.63 
99.97 
Localities where this stone is of suitable composition are not rare, 
but no other locality can be cited where the stone assumes a thickness at 
all sufficient for any extensive cement industry. It is usually of dense 
gray limestone, of 2 to 4 feet in thickness, which could not be profitably 
mined or stripped. 
Ferriferous.—The Ferriferous limestone, especially in its southern 
exposure, is a very important and promising source of cement stone. 
The area covered by this stone, in its exposures above drainage, com- 
prises an area about 6 to 8 miles wide and 40 or 45 miles in length, and 
amounting to about 300 square miles. In the western edge of this area, 
it is too thin to mine well, and its position near the tops of the hills makes 
the areas small. But on the eastern edge the areas are large, and but little 
dissected by valleys, and the stone is covered by strata suitable to make a 
‘good roof for mining it. Its thickness runs from 4 feet in the thin 
exposures to 10 feet in the best; 6 to 8 feet are its usual development. 
It can be won by mining or by stripping and benching around the edges 
of the hills. The point where the latter method ceases to be profitable marks 
the point where mining becomes possible. The chemical character of the 
stone is exceptionally well suited to cement manufacture. It is low in 
magnesium everywhere; it is usually well over 90 per cent. of CaCO, and 
frequently contains over 95 per cent. of this ingredient. Its iron is. 
generally low, favoring a light colored cement. (See table V at end of 
chapter. ) 
This stone is now being used as the basis of cement manufacture at 
some three well equipped works, which are turning out an excellent 
product. 
This stone on the northern edge of its field becomes thin and irregular 
and finally disappears north of Creola, Vinton county, and shortly after- 
wards the Putnam Hill limestone makes it appearance, in passing to the 
northeast. 
Lower Kittanning.—There is no other constant or well marked 
horizon of limestone of which sufficient quantity is found to be com- 
mercially interesting for several hundred feet above the Ferriferous hori- 
zon. Several formations swell up locally and offer for a limited area a 
