M( DOXOUGH COUNT V. 263 



and in the western part the subordinate limestones would be reached 

 at a depth of one hundred and fifty feet or less. When the light-gray 

 breceiated limestone of the St. Louis group is reached, it is useless to 

 bore further in search of coal, and this limestone is so decidedly differ- 

 ent in its appearance from any of the limestones in the lower part of 

 the Coal Measures, that an expert would find no difficulty in identify- 

 ing it, even by the smallest fragments taken up by the sand pump. 

 Hence, it forms a reliable guide, both where it outcrops and where it 

 may be reached by the drill, and determines the point below which no 

 coal can be found. 



Fire-cluy. The lire clay under the Colchester coal has been used by 

 Mr. Horrocks, at his kiln west of the town, for the manufacture of 

 drain tile, fire-brick, etc., but recently he has obtained a better quality 

 of fire-clay by sinking a shallow shaft down to the lower or Xo. 1 coal, 

 which, at his kiln, is about forty-five feet below the Colchester seam. 

 The horizon of this lower coal furnishes an excellent article of fire and 

 potters' clay in various portions of the State, and it may, no doubt, be 

 found at many points in this county, besides the one where it is at 

 present worked. 



Imn Ore. There is a band of iron ore. very generally developed in con- 

 nection with coal Xo. 1, and indications of its presence were observed 

 at several points in this county, though not in sufficient quantity to 

 justify an attempt to work it at the present time. On the creek below 

 Horrock's brick kiln it is about six inches thick, but too sandy to be of 

 much value, even if the quantity was greater. On the creek west of 

 Macomb. a band of very pure iron ore occurs, about six inches thick, 

 and it is quite probable it may be found somewhere in the county of 

 sufficient thickness to be of some economical importance. In Schuyler 

 county, there are two or three bands of ore associated with this same 

 coal, attaining there an aggregate thickness of about two feet, and 

 yielding on analysis about 52 per cent, of protoxide of iron. The ore is 

 an argillaceous carbonate of iron, and compares favorably in quality 

 with the best Pennsylvania ores. 



On Mr. D. C. Flint's place, in Mound township, a deposit of bog iron 

 ore of good quality is found, which is reported to be several feet in 

 thickness, but the area covered by it has not been ascertained. Should 

 it prove sufficiently extensive, and as pure as the sample sent to my 

 office, it is a valuable deposit. 



BuMlimj Stone. The central and western portions of the county have 

 an abundant supply of freestone from the sandstone bed intervening 

 between coals Xo. 1 and 2. This is usually from ten to twelve feet in 

 thickness, the upper part thin-bedded and quarrying out in thin, even 

 slabs suitable for flags, while the lower part is quite massive, and splits 



