346 



CENTRAL MINERAL REGION OF TEXAS. 



strike of the broad quartz bands. Prospecting in this locality would be 

 justifiable from the surface indications, but it seems probable that the north- 

 west trend is the one which carries the best ore. 



The Spiller mine is really a series of shafts and diamond drill borings 

 near the summit of a ridge of granitic and quartzose rocks, lying about two 

 miles west of south from Fly Gap. The ore is a rather siliceous psilomelane, 

 with patches of pyrolusite, and more or less black wad filling cavities and 

 crevices in the vein, which is three to four feet in width. 



The strike of the rocks here is north 36 degrees west — the Fernandan 

 trend — and the ore seems to lie as an interbedded vein The vertical shafts 

 have not followed the ore, which hades off to the southwest, in which direc- 

 tion a number of borings were made with the diamond drill. There is very 

 little development, and one can not, therefore, form a very correct idea of the 

 situation below. Such deposits are liable to be "pockety," but the outcrops 

 of this vein on the surface are somewhat persistent. Streaks of quartz run 

 through the ore rather irregularly, but a little care in blasting and sorting 

 will enable operators to bring the material to a marketable grade in consid- 

 erable quantity. Below are given analyses of several samples collected by 

 the writer: 



Water 



Silica 



Ferric oxide and Alumina 



Lime 



Magnesia 



Phosphoric acid 



Sulphuric acid 



Manganese protoxide. . . 

 Manganese sesquioxide. . . 

 Manganese dioxide 



Total 



Available oxygen. . . 

 Metallic Manganese 



11.4*7 



9.00 



3.05 



1.31 



Trace 



Trace 



56.63 



100.28 



9.20 



51.33 



46.15 



7.50 



8.90 



Trace 



Trace 



36.12 

 1.48 



100.15 



3.93* 



26 07 



43.10 



18.35 



9.74 



Trace 

 Trace 



29.04 

 Trace 



100.23 



22.48 



3.00 



19.13 



7.63 



0.73 



Trace 



66.64 

 3.06 



100.19 



7.31 



48.32 



*Analyst, L. Magnenat. 



Another field which has yielded some manganiferous ores, and which may 

 be worth prospecting for manganese ores, is that portion of the district be- 

 tween Packsaddle Mountain and the Riley Mountains in which the northwest 

 strike is at the surface. The occurrence here of quartz with manganese 

 stain and the similarity of the deposits generally to those in which the man- 

 ganese ores occur elsewhere, as well as the identity of structure in other par- 

 ticulars, all make it possible that the indications of ore point to much the 

 same conditions of accumulation as those existing at the Spiller mine. These 

 remarks are very general, but they can not well be more explicit until special 



