40 GEOLOGY OF ILLINOIS. 



miles south of Elizabeth, on the Mount Carroll and Galena road, the 

 Jenkins' pottery is located. This establishment has been in operation 

 for quite a number of years, and has built up quite a remunerative 

 business. The clay is obtained near by. It is not altogether pure and 

 free from foreign substances ; but these difficulties seem to be mostlj' 

 overcome by the processes through which it is put in manufacturing. 

 The result is, a ware largely used in this part of the State, as the Jen- 

 kins' pottery wagons are well known, in all the neighboring towns, vil- 

 lages and cities. 



Common yellow and red clays, for ordinary brick, exist everywhere in 

 the greatest abundance. Sand, suitable for building purposes, is not so 

 universally distributed, neither is it so scarce as to be a matter of seri- 

 ous inconvenience. 



The Associate Minerals. Associated with the galena, and deserving 

 a passing notice before that important mineral deposit is referred to, 

 are several other mineral substances well known in the lead region. 

 The most important of these is the sulphuret of zinc, blende or "black 

 jack" of the miners. This is a useful ore of zinc, but is quite difficult to 

 reduce. In the lead region it is not considered of economical value. 

 The carbonate of zinc, smithsonite or "dry bone" of the miners, is con- 

 sidered a more valuable mineral. A furnace for its reduction has been 

 in operation for some years at LaSalle, and has proved a financial suc- 

 cess. Iron pyrites also occurs in connection with these minerals, in con- 

 siderable abundance. At the celebrated Marsdeus' lead, all these asso- 

 ciate minerals may be seen associated with each other and with the ga- 

 lena, with the Galena limestone, and with spar and other substances. 

 This mine has afforded the best cabinet specimens of these minerals in 

 combination to be "found anywhere in the lead regions. Brown hema- 

 tite, and several other mineral substances, occur in occasional small 

 quantities, but they are not of interest, in an economical point of view. 

 None of these associate minerals have become articles of commerce, ex- 

 cept, perhaps, the carbonate of zinc ; and it is doubtful if even that ex- 

 ists in sufficient quantities to make it an article of value in the economi- 

 cal resources of this county. 



Galena or Lead Ore. The great mineral interest of the county, as 

 every one knows, is lead. Indeed, it is second to no mineral interest in 

 the State, except that of coal. The leading ore of this metal has given 

 its name to the great and important rocky formation in which it is 

 chiefly found in this part of the country, to an important city in the midst 

 of its heaviest deposits, and to the township in which that city is lo.- 

 cated. 



The scope of this county report does not embrace a very extended es- 

 say upon the mining or metallurgy of lead, or a topographical survey or 



