BUILDING MATERIALS. 369 



The color is red or dark reddish-grey, and there is a considerable range of 

 choice. In combination with the other granites, by judicious alternations or 

 different modes of treatment, but little is needed to obtain the widest variety 

 of ornamentation of which the darker granites are capable. There are other 

 exposures of " dimension granites " in situations which make it possible that 

 they belong to a different uplift from that of the Capitol Granites. In the 

 Wolf Mountain, north of Llano in Rabb's pasture, a rock of this character 

 has been locally applied with success in building small structures. This has 

 features which place it in a transitionary position between the block granites 

 and the Capitol granites. It has an attractive appearance, being more nearly 

 purple or blue in color than its red-grey compeers. 



Dimension granite also occurs in abundance in some variety in the belt 

 which runs through the Archaean rocks in Burnet County, extending from 

 Capitol Rock, between Spring Creek and Clear Creek. It is probable that 

 the rough country in this tract is made up of outbursts of different ages. 

 Some quarries have been opened in the area and good material has been ob- 

 tained, but the demand has not yet caused any extensive development of 

 these resources. 



It is a mistake to suppose that the dimension granite is restricted to the 

 Post-Carboniferous uplift, to which the Capitol granite belongs, for there are 

 important outcrops in other masses in various parts of the region. 



G. THE FISSILE GRANITES. 



The Cretaceous uplift brought up a class of granite of somewhat irregular 

 character but commonly fissile, bearing Dorth 30 degrees east in the out- 

 crops. Some of these are possibly of some value for the more severe uses, 

 but they are not likely to attract especial attention, owing to their general 

 inferiority to the neighboring Capitol granites. But there is variety enough 

 in intimate texture to make some of these possibly useful for trimmings and 

 for particular purposes. In the neighborhood of Enchanted Rock upon the 

 east there is a line of elevations, including Sentinel Peak, which appear 

 to owe their resisting power to infiltrations of beautiful porcelain-white quartz, 

 which has filled the interstices and produced a rock of some possible orna- 

 mental value. There are other fissile granites and gneisses in the dif- 

 ferent uplifts, some of which may be of economic importance, but none of 

 them have yet been tested. 



2. THE MARBLES. 



There are at least three possible sources of marble in the Central Mineral 

 Region, although it is not now practicable to report just how valuable these 

 may be. The surface outcrops are not always the most reliable indications 



