210 GEOLOGICAL RECONNOISSANCE 



the best information, is that the ore was rather more abundant at the 

 greatest depth reached, than near the surface, as if it, might concentrate 

 into a true vein. For want of sufficient capital to sink deeper, these 

 mines have never been thoroughly proved. 



Associated with the lead at Houghton's diggings, is a yellow, earthy- 

 looking rock, resembling indurated mud; hence, labeled mudstone, which 

 proves on examination to be remarkably rich in carbonate of zinc; for the 

 chemical constituents of this ore, see the Chemical Report. 



Many other localities in this county have afforded some lead. On the 

 headwaters of Reed's creek, on the property of Mr. Robert G. Shaver, 

 township 15, range 4 west, lead ore is found, associated with carbonate of 

 zinc and zinc-blende (sulphuret of zinc). At this place, digging has only 

 been made to the depth of two or three feet, entirely insufficient to prove 

 the richness'of the deposit. The crevices in which the lead is found, tra- 

 verse the strata in a north-east and south-west course. This locality has 

 the appearance of being a very favorable place in which to find a good 

 vein of galena; at least, it is worthy of a more systematic search than has 

 yet been made. The rocks in which this lead occurs, belong also to a and 

 b of the section. 



Carbonate of zinc, belonging to the variety known as "smithsonite," is very 

 abundant in this county, and, for the purpose of converting this ore into 

 the metallic zinc of commerce, works have been erected by a company of 

 gentlemen from St. Louis, known as the Independence Mining Company. 

 Their works are located on section 22, township 16 north, range 4 west, 

 and are called " Calamine," after the zinc ore of that name. 



So far as can be ascertained by the present openings, the zinc ore does 

 not run in veins or crevices, but occurs in beds, associated with a red ferrugi- 

 nous clay, resting on a dolomitic limestone. Both the matrix of red clay 

 and specimens of the associate limestone, which were analyzed by Win. 

 Elderhorst, M. D., the Chemist to the Survey, have been found to contain 

 a small per centage of zinc. The ore, imbedded in the clay, is usually of 

 a porous or cellular character; but sometimes compact, and covered with 

 crystals stained with oxide of iron. That which is found in contact with 

 the dolomitic bedrock, is mostly in mammillary or botryoidal masses, hav- 

 ing an opalescent appearance on the fresh fractured surface. The corro- 

 ded and irregular surface of the dolomite seems to indicate that large por- 

 tions of it must have been removed, perhaps by some material inter- 

 change of the elements of the rocks and the metallic solutions pervading 

 it. The small fractures, which traverse this bed rock in every direction, 

 are, at some of the localities, filled with beautiful rose-colored crystals of 

 carbonate of zinc, resembling pearlspar. 



