PIKE COUNTY. 617 



of this substance is found throughout the whole series. Spheroidal con- 

 cretions — often quite symmetrical in form,, and varying in size from an 

 inch or two in diameter to five or six feet — abound in the middle portions 

 of the series. At the centers of these concretions, as they occur to the 

 northward in the State, very interesting remains of fossil fishes have 

 been found ; but the only fossils noticed in concretions here are of vege- 

 table origin, and these are very rare. 



The shales are charged with a large amount of soluble matter, and 

 as their texture sometimes allows a very free percolation of water, the 

 springs that issue from them are to a considerable extent mineral 

 springs. Sulphureted hydrogen, compounds of iron, silica, lime, magne- 

 sia, and soda are found in many of them. When the water holding these 

 materials is evaporated, as it must be when oozing from the beds of shale 

 in weak springs, these mineral contents are deposited in beds of traver- 

 tine, sometimes of considerable extent. These travertines, so far as ex- 

 amined, are all qchreous— sometimes, indeed, being so rich in iron as to 

 constitute strong and excellent ores. The composition of two specimens 

 is shown by the following analysis made by Prof. T. G. Wormley, Chem- 

 ist of the Survey. No. 1 is from Grassy Fork, No. 2, from Idaho : 



No. 1. No. 2. 



Silicious matter 33.20 8.85 



Sesquioxide of iron 50.80 73.08 



Lime 1-10 1.30 



Magnesia, carbonate 0.23 0.53 



Phosphoric acid 0.06 0.10 



Water, combined 14.45 16.00 



99.84 99.86 



Metallic iron 35-5 6 51.16 



There is every reason to believe that the amount of lime was originally 

 much larger in the travertine. Atmospheric agencies would necessarily 

 remove this element from all exposed portions of the deposit. The supply 

 is too limited to make these beds of account in iron-making. As sources 

 of ochre they promise better, but it is doubtful whether economical work- 

 ing of such capricious supplies can be effected even for this limited use. 



The points at which the ochreous tufas have been found to occur in, 

 largest quantity are on the Grassy Fork of Sunfish Creek, two miles 

 above its mouth, and on a small tributary of Sunfish Creek that enters 

 it quite near to Idahfo. 



In the last named neighborhood a few fragmants of metallic antimony 

 were found a few years since, and the discovery caused considerable local 

 excitement. It is safe to say that the metal was dropped at the place- 



