612 CENTRAL MINERAL REGION OF TEXAS. 



rocks, and it might be doubted whether there is actually a continuous bed, or 

 set of beds, forming a definite horizon in the Fernandian System. At first 

 sight some of the outcrops comport nearly as well with the idea that they are 

 "lenses" or "bosses" of ore brought into their present positions by local 

 causes. But it has been found that while the large masses may be apparently 

 discontinuous across the region, there is almost always rn indicator of con- 

 tinuity in the shape of a line of ferruginous soil or other landmark; and 

 when the undecomposed hard ore again presents a topographic outline of its 

 own it invariably possesses the same character as its representatives in the 

 same band. This statement may be verified by any one who will take the 

 trouble to note the positions of the bright red soil belts which are successively 

 crossed in traveling between Lone Grove and Camp San Saba, on the Burnet 

 and Brady road, or in traversing an equivalent stretch of country by almost 

 any other route. It is also a very interesting fact that the derived, or second- 

 ary, iron deposits of later date in the basal Cambrian strata at least follow 

 roughly the same trend, though in a much less pronounced manner. These 

 facts come out very strongly upon the accompanying Economic Map. 



The area in which the Fernandian beds, prevail as surface rocks may be 

 limited for the present practical purposes by northwest-southeast lines drawn 

 through Lone Grove, Llano County, upon the east, and through Katemcy, 

 Mason County, upon the west. This blocks out a district thirty miles wide 

 and extending perhaps thirty miles in the direction of the strike. Within 

 this field, however, various structural features have prevented in many places 

 the outcropping of the iron bearing system, so that a part of the area is not 

 in a condition to yield ore without removing thick deposits of later origin. 

 Besides it must be understood that only a small fraction of the thickness of 

 these strata is iron ore. Keeping in mind also the folded condition of the 

 rocks, it is evident that the chances for mining will be dependent largely upon 

 the character of the erosion, it being premised that the iron stratum is not 

 very near the top of the system to which it belongs. 



The Iron Mountain Series, which includes magnetites, was described in 

 some detail at page 271, et seq., in the Report for 1889. The horizon of the 

 magnetic ores is near the middle of the Fernandian System and below the 

 middle of the Iron Mountain Series. 



The iron deposits lie between carbonaceous and calcareous beds which 

 overlie them and quartzose beds beneath. Knowledge of these facts will 

 assist greatly in the search for the ore; for wherever the graphitic schists 

 and marbles appear at surface, as is the case for instance just west of Llano 

 Town, the iron stratum is buried, and wherever the quartzose beds outcrop 

 the hard iron ores must be sought in positions above them. A warning is 

 necessary, however, against confounding the more granular and less meta- 



