MINERAL RESOURCES OF THE STATE OF NEW YORK 303 



Copper was not reported, but it is present in small amount in 

 most samples. Silver was present to the extent of 2.25 ounces to 



the ton. 



The general inference as to the origin of the deposits from consid- 

 eration of these features is that they were formed by underground 

 circulations directed along the fissure zones and bedding planes of 

 the sandstone. The tendency of the minerals to occur in crystal 

 particles, the frequent occurrence of vugs, and extreme variation in 

 proportions of the metallic ingredients may be noted. The source 

 of the ore-bearing solutions and their character are matters which 

 can not be discussed advantageously at this time. It may be noted, 

 however, that there are no igneous bodies exposed in the vicinity 

 and the only intrusions in southeastern New York that have taken 

 place subsequent to the period of the formation of the sediments 

 is the Triassic trap in Rockland county. The presumption that the 

 waters concerned in the ore-deposition were shallow and suppHed 

 from the surface, comparable to the body of underground water in 

 circulation in the beds at present, would seem to be most in accord 

 with the general conditions. However, an interesting observation 

 has recently been communicated to the writer by R. J. Colony with 

 respect to the country rock, who found on examination of the sand- 

 stone that it contained secondary minerals, evidencing the effects 

 of metamorphism which are ordinarily ascribed to igneous agencies. 

 The problem requires further investigation before it can be satis- 

 factorily treated. 



The question of source of the metals is bound up more or less with 

 the preceding one as to their carrier and solvent agency. Lime- 

 stones are found to carry zinc and lead and they form the containing 

 rocks for many of the large deposits mined throughout the world. 

 They are more likely to have been the immediate source of the 

 metals than the sandstone. There are two important areas of 

 carbonate rocks in the region, one lying under the valley at the foot 

 of the Shawangunk ridge, and composed of the Helderberg and 

 Onondaga limestones, and the other the belt of Precambrian lime- 

 stones of which no outcrop is to be seen in the immediate vicinity, 

 but which occur to the southeast in the Wallkill valley as an exten- 

 sion of the New Jersey belts. The former overlie the sandstones 

 and the latter are separated from them by a considerable thickness 

 of shales of the Hudson River group that outcrop on the eastern edge 

 of the ridge and occupy a position below the Shawangunk beds. 

 The nearest exposed area of the Precambrian series is several miles 

 distant, but it is not improbable they may occur in depth within 

 easy reach of the ridge if not actually below it. 



