648 CENTRAL MINERAL REGION OF TEXAS. 



tion facilities shall enable the product to be marketed. There does not seem 

 to be a prospect of the establishment of a very extensive industry upon this 

 material as a basis, and yet the outcrops are such as to warrant development 

 in a number of cases. Some of the more dense varieties, of a pure snow white 

 hue, will serve well as ornamental stones in the higher type of buildings, and 

 if obtainable in blocks of proper dimensions they may also be employed for 

 heavier construction. It is not probable that the quantity will be found suf- 

 ficient for the support of a very considerable industry. 



THE SILURIAN "MARBLES." 



The variety of calcareous rocks in the Silurian System of Central Texas is 

 very great. Many of them are wholly unfit for use in construction except in 

 situations where they are hidden from view. Others, which have little else 

 to condemn them, are often not procurable in large blocks, owing to the 

 numerous joints which traverse the deposits. Still others which can be quar- 

 ried in good form of suitable sizes are of undesirable color or texture, giving 

 them but limited application in the arts. But in addition to these there are 

 not a few stones which possess great intrinsic value, some of them being 

 highly ornamental. Much of the so-called "lithographic stone" is of this 

 character. Although not always 'adapted to the very refined needs of the 

 lithographer, the polish which such rock acquires under manipulation may be 

 fully adequate to the demands of the builder's art even in some of its more 

 artistic forms of expression. 



The general distribution of the Silurian System is given by the hachures 

 drawn downward from right to left upon the Economic Map herewith. The 

 whole of that tract is not covered by suitable deposits for commercial use, 

 but the area which is not so hachured may be taken as practically free from 

 any occurrences of the kind. The so-called marbles, excepting a few of lim- 

 ited extent, are of the type now known as " Burnet marble," although this 

 term was not, I think, originally employed in so wide a sense. There are 

 some interesting cases of local super metamorphism and of calcite veins car- 

 rying material well enough compacted to serve as marbles. These occur in 

 several places in Burnet County, and from them the general name was prob- 

 ably derived. But they are of restricted distribution, and the more abundant 

 tougher beds of the Hoover Division of the Leon Series are those which 

 are commonly referred to as "Burnet marbles." Some of this material has 

 been quarried in different places in the belief that it might be available as 

 lithographic stone. 



The Burnet marbles vary greatly in color, texture, and weathering. They 

 are usually tough and compact, admitting of a fine polish. Some are even- 



