THE IRON ORES OF EAST TEXAS. 79 



above the sea level. The top of the hill is covered by a stratum of compact 

 iron ore and ferruginous sandstone, about two feet in the thickest part seen. 

 The ore appears to be sometimes interstratified with the sandstone, and at 

 others to be segregated in it. On this property was located the old Sulphur 

 Forks furnace, which was worked during the Civil War. Similar deposits 

 are to be found in many places in Marion and Cass counties. The ore is 

 generally associated with mottled clays, and interstratified clays and sands, 

 and the thick bed of red sandy clays shown in the Johnson Hill section. Oc- 

 casionally, as between Kilgore and Atlanta, the ore is underlaid by a pure 

 white sand, associated with the other beds mentioned above. Underlying 

 the sands and clays of the iron bearing formation, is a bluish-gray clay, 

 sometimes sandy. In this bed clay ironstones have been found in digging 

 wells. They are of a light gray color inside and brown from oxidation on 

 the outside. Going west from Marion and Cass counties, similar iron ore is 

 found in the adjoining country. In Van Zandt County the ore thins out, 

 and entirely disappears in its western limits. 



ORIGIN OF THE NODULAR OR GEODE ORES. 



These ores, as has been stated, are all associated with sands and clays 

 in horizontal or almost horizontal beds, and apparently conformable with 

 the underlying and overlying strata. The existence of these ores, often 

 between two non-ferruginous strata, would seem to preclude the possibility 

 of their origin from external sources, and consequently it is necessary 

 either to account for their presence from a local source or to suppose them 

 originally deposited with the associated strata in the same form as they 

 are found now. This latter supposition is not probable, as the structure 

 of the bed is not such as would be expected in such a deposit, nor does 

 the ore partake of the nature of a bog deposit. There is very little iron py- 

 rites or glauconite present, and consequently they can not have participated 

 in its formation, as in Cherokee County. There are, however, large quanti- 

 ties of clay ironstone nodules in the unexposed strata below the ore bed, and 

 they are frequently found in digging wells. They are composed of carbon- 

 ates of iron and lime, with alumina, silica, and other ingredients in smaller 

 proportions, and there is strong evidence that the brown hematite is the re- 

 sult of the decomposition, in place, of such nodules. They are rarely in a 

 continuous bed, but usually in flat lens-shaped masses, one to six inches thick 

 and one-half to three feet long, and often laid in horizontal beds very close 

 to each other. These nodules are in their undecomposed state of a gray color, 

 very hard and heavy, and often show shrinkage cracks in the interior. They are 

 generally, however, partly decomposed into peroxide, and have a hard brown 

 rusty crust, weathering off in concentric layers, and varying in thickness with 



