49
We may judge better of this when the geologic section is worked out in detail. How well this is done must depend largely upon the funds available for office work in this division of the Geological Survey.
V.—MINERAL RESOURCES.
The Cretaceous strata, aside from the building stones and materials for lime and cement manufacture, are not usually regarded as prolific of economic value, although many are prone to look for gold and silver in all new countries. We shall see that there is enough variety in the deposits of this territory, however, to give promise of reward to well directed mining industry in several important directions.
ORES OF METALS OTHER THAN IRON.
Within the border area, including the greater part of the thirteen counties of the fourteen (Gillespie excluded) named in our title, there is little possibility of discovery of valuable ores of gold, silver, tin, lead, zinc or other high priced metals. Copper ores, such as may possi- bly occur in Permian strata near the edge of the district, have not come under my own observation, and these rocks are practically all within the field of operation of another member of the Survey. The veins which have been found in conjunction with the basaltic dykes in Uvalde county, as on Turkey creek and near Montell, have been supposed to carry ores of silver. Very small amounts of galena and copper pyrites have been discovered in such situations, and it is in these places that discoveries of the kind may be anticipated, if anywhere in the region. The prospect is not very favorable, the indications being lean and unpromising, as far as they have been tested heretofore.
Deposits which may become valuable in the manufacture of aluminum are not wanting, but in the present stage of production they are not liable to be called into play as the basis of any considerable industry.
IRON ORES.
The ores of iron which occur in the district are wholly unlike those described in the previous reports from the Central Mineral Region. They may be conveniently grouped in three classes, distinguished by their modes of occurrence.
To the first class belong the bedded masses of yellow and red ochres, which appear to have been formed along the shores of the earlier Cre- taceous seas by the degradation of the pre-formed rocks of the Central Mineral Region type. These outcrop more or less regularly at definite horizons near the base of the so-called Cretaceous system, but they are only occasionally of such a character as to merit attention as commercially valuable ores. Frequently they are too highly siliceous, and"
Prof. W. F. Cummins. Geologist for North Texas.