copper. 335 



junction of these two or three ancient trends, especially where the dips of the 

 different systems are unequal, will make mining difficult, as it will necessitate 

 a thorough knowledge of the rocks and of the local strikes and dips of the 

 Burnetan, Fernandan, and Texan systems. Besides this, the slips, faults, and 

 contortions make a complicated underground structure, which not only re- 

 quires much study to follow it properly, but it is also liable to cut out the ore 

 bodies or make infiltration impossible. Still, any vein which shows well at 

 surface has probable continuity in depth, or it would not have been brought 

 to light. The deposits which can certainly be made out to be associated with 

 igneous rocks of the north-south trend are most probably the easiest to fol- 

 low, because that is a late uplift in the afterward little disturbed copper belt. 

 But it is not probable that the richest ores lie in this trend at the surface ; on 

 the contrary the assays made for this Report give the best record to the most 

 ancient course — north 75 degrees west, the one in which the silver ores chiefly 

 occur. 



A. THE BABYHEAD DISTRICT. 



The Babyhead District is the best copper region now known in Central 

 Texas. The ores at surface are largely carbonates, both azurite and malachite, 

 the latter predominating. Tetrahedrite (fahlerz) is more or less common, occa- 

 sionally, but not always, carrying a notable amount of silver. Chalcopyrite is 

 sometimes present, but usually not in much abundance. None of the dig- 

 gings have gone below the zone of surface action, and as many of them have 

 not followed the veins, it is difficult to form an opinion as to economic values. 

 Results of assays of my samples are given in Table I, with localities. Below 

 are brief descriptions of the principal workings, beginning upon the east at 

 Little Llano Creek. 



HOUSTON AND TEXAS CENTRAL RAILROAD DIGGINGS. 



On railroad land (section No. 3, survey 1239) near the mouth of Yoakum 

 Creek, north side, there is a peculiar ridge of hornblende rock, or of schists 

 with a hornblendic belt or belts running through them. The appearance at 

 the diggings near the summit of the ridge is that the north 75 degrees west 

 (Burnetan) trend is the course of the copper- bearing band, but the strike 

 of the schists is apparently northwest (north 36 degrees west — northwest, 

 magnetic). A semblance of a north trend is also visible, but there is little 

 evidence of a strike in that course. The rock is stained with malachite, which 

 also partly saturates porous masses. Some parts contain a little epidote, and 

 magnetite is abundant in places in fine grains. According to the proportions 

 of the iron ore, the specific gravity of the gangue varies from 3.277 to 3.978. 

 (Table I, No. 4.) 



