REPORTS OF THE BUILDING COMMITTEE. 607 



As already remarked, iron pyrites (bi-sulphuret of iron) occurs occasionally in 

 these marbles, in nests, both at Worthington's and Baker's quarries ; see specimen 

 10 p. This mineral is much prone to undergo chemical changes by the action of the 

 oxygen of the atmosphere ; the sulphur passes into the state of sulphuric acid, the 

 iron into oxide of iron, forming copperas or bi-sulphate of iron, a salt easily soluble 

 in water, which is gradually removed ; leaving, of course, a cavity in which water 

 may lodge and freeze, whilst at the same time the oxidation of the iron spreads a dis- 

 agreeable ferruginous yellow stain around the spot. For this reason great care should 

 be taken, in selecting marble, to reject all masses contaminated with this mineral. 



The only locality in the neighborhood of Worthington's quarries where a marble 

 of the structure of the " alum stone " was observed, is in the immediate vicinity of 

 his dwelling house ; here, for a short distance, a white marble of that texture occu- 

 pies the surface. Three hundred to four hundred yards beyond, on Prospect Hill, at 

 a height of two hundred and twenty-one feet above the bed of the northwest branch 

 of Beaver Dam creek, a highly ferruginous mica slate, charged with garnets, reaches 

 the surface : this seems to be the boundary of that formation on the east. This gar- 

 netiferous micaceous schist may possibly serve to define the limits of the white marble 

 formations, and may, perhaps, be the means of detecting these metamorphic marbles 

 elsewhere. 



One mile north of Texas, close to the railroad, is a quarry owned by Chisilla 

 Owens, and now worked by Mr. Cooper. The rock here is weli bedded, and may be 

 quarried with ease ; but the beds are, for the most part, thin, and there is an inter- 

 lamination of mica. Here the dip is to the northeast, in an opposite direction from 

 what it is in the Texas quarries. There is a bed of white crystalline marble (" alum 

 stone ") in this quarry, of about two to two and a half feet thick ; whether it extends 

 of uniform appearance and thickness through the hill, is not clearly seen in the pres- 

 ent state of the quarries. The blocks lying in the quarry are of very regular dimen- 

 sions, and the surface comparatively even, but they are not large, and many of the 

 beds are interlaminated with mica; see specimen No. 11. 



In the vicinity of Texas is a quarry owned by Judge Nesbitt, which has afforded 

 some good white marble of a rather finer grain than that of most of the quarries in 

 this vicinity ; see specimen No. 12. I had not an opportunity of examining this 

 quarry in person. 



South of Fell and Kobinson's quarry at Texas, on land owned by Mr. Cockey, 

 there is some fine, white, close-grained crystalline marble. It lies, however, low — 

 not more than eight or ten feet above the bed of Cold Stream creek. The quarry is 

 not open, so that one cannot judge of the bed. Mr. Cockey says the same kind of 

 rock has been found half a mile west. This is the only proof of its being extensive. 



On the whole, it appears that there is a region of country extending for about two 

 miles from north to south, and three-quarters to a mile from east to west, occupied 

 by this marble, extending from the level of the water courses to forty to forty-five 

 feet above the same, and constituting the whole of the hills within this tract of coun- 

 try ; not all of the purest white, but varying from a snow-white to a light blue. It 

 may be estimated that about one-third is of tolerable purity, and either of the crys- 

 talline texture or of the fine-grained crystalline structure, approaching in quality to 

 the Carrara. 



Nor can this be considered the limit of the formation. Scott's quarry, five miles 

 beyond these, in the vicinity of the railroad, supplied a portion of the material for 

 the Washington monument at Baltimore, and other quarries of white marble were 

 pointed out to me from Prospect Hill, several miles off. 



It cannot be doubted that these quarries are capable of supplying an unlimited 

 amount of fine building material, either of the fine-grained marble or of the " alum 

 stone." Whether the former could be obtained for the entire Smithsonian building, 

 of a uniform color, free from gray spots and veins, is less certain ; though Worth- 

 ington confidently asserts, if he be permitted to supply white and faint blue indis- 

 criminately, similar to specimens Nos. 10 w and 10 bl, he can furnish far more than 

 the building requires, without blemish. 



From all I have seen and heard, I incline to believe that the fine-grained marble 

 will be somewhat more expensive to cut than the " alum stone ;" but, on the other 

 hand, if the ornaments have bold projections, and much undercutting, the coarser 

 " alum stone " is unsuitable; it chips off more readily, and is less tough than the 

 finer-grained varieties. 



The " alum stone," as far as I can learn, works much like the Westchester marble ; 

 and if in the latter all the necessary Norman ornaments can be cut, so can they also, 

 most probably, in the former. 



