BUILDING SIONE. 623 
and the fossil corals are sometimes composed of silica, which also is 
distributed through some of the stone in bands that separate the layers. 
In composition the stone is nearly a typical dolomite, as is indicated 
by the following analysis: (6) 
Per cent. 
Gal ChIMMACATOOMALE Merete nec e rear et ae Nec etl Sealoveinen tetlenaneceis ovencvace Gey 'e 53.67 
IWreM EST CFE SOLES? 650006000000 860 000.000 056 650. 000.900 650905 40 dssHoDBEO.G66 cogGoGGeG hy!) 
Alumina and ir0n ......ccseseeseseeeeessereeeeeeesteeees teens eeeeeeseseee sense sevees 1.30 
Calciummandsmagnesitmisilicateseercutecscmssetessesccscieseon iced: osace 1,44 
Sit CAPE Reece ac coe eacisee can ctie sine coerce Sats celonciese sacbustesm'ss'arccs Uvewiss 1.00 
ING teal Te eee netic cates cic oeonte eles oe eae ane se ani oa dacs cats dereentahe rey OID 
When examined under the microscope the whole stone shows the 
characteristic crystalline granular structure of the Helderberg formation. 
There are streaks of iron oxide and carbonaceous matter which proceed 
in regular wavy lines through the sections, and these bituminous sub- 
stances are what give to the stone the strong fetid odor which is produced 
by striking or cutting it. The quality of the lime produced is another 
evidence that magnesian limestones may be converted into lime of ex- 
cellent quality. . 
Quarry operations have been carried on at Greenfield since the first 
settlement of the country, to satisfy the local demand, but in recent 
times the business has been greatly enlarged for the more distant markets 
along the line of railroads, and especially for the Cincinnati demand. 
The supply of stone is practically inexhaustible. 
In the southern and western part of Champaign county the Helder- 
berg or Water-lime rocks have been quarried in numerous places ; 
formerly a quarry at Salem supplied most of the local demand, and the 
building and flagging stones used in Urbana were obtained there until the 
sandstone of Bereasuperseded them. The stone obtained in the neighbor- 
hood of Urbana is of indifferent quality for building purposes, but here 
it is found in a drift-covered region in an area which for 25 or 30 miles 
‘in each direction is devoid of stone. Only about 14 feet of the upper 
strata have been much quarried. The floor has been sunk to a greater 
depth, and the stone from the lower courses is proving itself to be a 
valuable building stone for rougher work. There is no so-called cutting 
(b) Report of Progress of Geological Survey of Ohio, 1870, p. 287. e 
