616 GEOLOGY OF OHIO. 
Dayton. A section of this stone was treated with dilute acid, when 
everything dissolved with the greatest facility, with the exception of 
‘these porphyritic crystals, which may consequently be supposed to be 
rhombohedrons of dolomite which have developed themselves in the 
mass of calcite. Although stones of such excellent quality are obtained 
from the Dayton beds, it is necessary to mention that stones occur 
in which pyrites exist in large crystals at least half an inch square. 
Pyrites is recognizable in the thin section of all specimens sent to us, 
though this ingredient is not so disastrous in a stone of this nature as it 
is inother more porous stones, in which the pyrites would not merely be 
reached much quicker by the decomposing agencies, but in which the 
products of decomposition would more quickly find their way through 
the cracks and crevices of the stone. The material has attained a high 
reputation. It has been more or less used at various points, as Chicago, 
Louisville, Columbus and Toledo. Cincinnati has used it largely, but 
for the last 15 or 20 years it has not been shipped so extensively to these 
points. 
Beds of the Dayton limestone are developed in Clinton county. 
They have been quarried at Wilmington and Centerville, but the old 
quarries which have been reported as in active operation during the 
census year are situated 14 miles southwestward from Lumberton. The 
quarry consists of 5 feet of stone, which is mostly used for rough building 
purposes, and is overlaid by 2 feet of drift. The material is hard, very 
compact, and capable even of assuming a quite high polish. It 1s also 
very noticeable that the rock, which to the unaided eye appears so com- 
pact and non-fossiliferous, really contains a very great number of fossil 
fragments. It also contains some pyrites, distributed through the mass 
in the form of very sharply defined cubical crystals, which in the speci- 
mens sent are entirely invisble to the unaided eye, and which cannot be 
called deleterious. There are yellowish spots and streaks in some of 
the layers, but this appears to result from the inclusion of clayey material 
rather than from the oxidation of the iron sulphide. The stone from 
this quarry finds its market principally in Clinton and Fayette counties. 
The rocks in Clarke county (c) are like those found in Montgomery 
and Greene counties, but the important quarrying operations are all 
carried on in the upper beds of the Niagara formation, which are typi- 
(c) Geological Survey of Ohio, Vol. I, Part i, p. 450: Geology of Clarke County, by Edward 
Orton. 
