356 CENTRAL MINERAL REGION OF TEXAS. 



rendering it crumbly, but much less commonly than in regions such as 

 Western Arkansas, where this process has acted excessively in carboniferous 

 rocks. 



There is a considerable variety in the segregations, and it is not always easy 

 to learn what circumstances have caused these differences, or whether there 

 is any natural order of arrangement of the products. The conviction is 

 strong that the nodular, concretionary, and streaky types are nearer the base 

 than the disseminated, cementing, and friable kinds, but much special study 

 must be given to these points before definite conclusions can be deemed ad- 

 missible. An interesting hint is given by the assays, some of which, al- 

 though reacting as hematites to blow-pipe and physical tests, are founds by 

 analysis to yield small portions of water. 



(3) THE HEMATITE SANDSTONES. 



Usually overlying the segregated ores, where these form a distinctive 

 stratigraphic horizon, are strata of sandstone of a peculiarly rich blood-red 

 color, varying much in texture and compactness. Some of them are exactly 

 what some of the red sand soil of the magnetic belts would be if it were re- 

 silted and hardened; other portions are similar, but variegated by laminae, or 

 partings, of pure white sand, and among them is a remarkable granular hem- 

 atite sandstone, often with the grains not firmly cemented together. This 

 last has often the reactions and physical characters of beauxite, but the per- 

 centage of water is too small for this mineral. 



The chief commercial value of this set of rocks will depend upon their 

 capacity for being washed or "jigged" to free them from the siliceous base. 

 Many of them will be useless for this purpose, and fortunately it is not at all 

 likely that it will be necessary to resort to such methods in this district, ow- 

 ing to the abundant supply of far richer ores, carrying higher percentages of 

 iron, which would readily deceive even experienced metallurgists if "judged 

 wholly by appearances. 



Table III gives analyses of a fair assortment of the three kinds of hema- 

 tite here described. As previously hinted, there is another class of pure, 

 coarsely crystalline, specular hematites, which have sometimes been mistaken 

 for high grade silver ores. These may appear to a novice like "grey copper," 

 but they are not minutely crystalline, and they exhibit a blood -red streak 

 when scratched by a knife or other hard substance. 



These ores occur in white quartz, usually only in such small proportions to 

 the gangue as to make them valueless for use in the iron industry. Occa- 

 sionally, as in the vicinity of the Kothman "Water Gap, east of Fleming Post- 

 office, there are pockets or possibly workable? masses of such ore; but I 

 regard all such cases as indicators of the occurrence of iron in the region 



