64 GEOLOGY OF THE SECOND DISTRICT. 



Character of the Primitive Limestone as a ?nining rock. 



Though few rocks are more productive in simple minerals than this, yet judging from wliat 

 lias resulted from numerous explorations in it, it does not appear to contain large deposits of 

 the useful minerals ; and even where veins or beds occur in this rock, there is not so much 

 constancy in the amount of ore, or in the direction it pursues, as in the harder rocks. Wher- 

 ever, for example, the speculcir oxide of iron occurs in it, it is in insulated masses ; or if it 

 is in a vein, it runs out, both below, and in the direction of the strike ; and so completely are 

 all traces of it lost, that it is impossible to determine in what direction it may be pursued in 

 order to recover it. Such is the experience, so far as it goes, in relation to this ore when 

 enclosed in this rock ; and I may make the same discouraging remark in relation to the sul- 

 phuret of copper, which has been found in it in many places, though not in veins, but in 

 masses which are called by miners nests, pockets or bunches of ore, which rarely contain 

 more than fifty pounds, and frequently only a mass sufficiently large for a cabinet specimen. 



We have not as yet, however, sufficient experience to enable us fully to establish the cha- 

 racter of this rock ; but so far as it goes, it is unfavorable for extensive and safe mining 

 operations. In this respect, it appears very much like other rocks of igneous origin, in which 

 sublimations of mineral matter have sometimes taken place ; or rather, as if the mineral had 

 been enclosed accidentally while in a state of ignition. Speculation, however, is of very 

 little use in the present state of our knowledge ; as we are not yet in the possession of a 

 sufficient number of facts to enable us to determine the constancy or inconstancy of the 

 mineral productions which have been observed in this rock. When metalliferous veins come 

 up for description, I shall have occasion to give more in detail the facts which have fallen 

 under my notice. 



Simple minerals which have been obset^ved in Primitive Limestone. 



The most common are the following : 



Mica, of various colors, as olive green, in fine crystallized six-sided tables. 



Tourmahne, in brown crystals, frequently fine and perfect, and rarely in small green crys- 

 tals, in Chester ; also yellow crystals, and translucent. Essex county. 



Hornblende and scapolite, in good crystals. 



Fluor spar ; carbonate and sulphate of strontian ; the former at Muscolunge lake, the 

 latter in Gouverneur. 



Sulphate of barytes ; sulphuret of iron and copper ; specular oxide of iron. 



Quartz, in dodecahednd crystals, in Edwards. 



Serpentine ; sphene, and phosphate of lime, in Rossie, where it is sometimes red. 



Rutilc, in Chester. 



Fine crystals of feldspar, in Rossie. 



Spinelle ; rcnsselaerite ; pyroxene, in fine crystals, and very conamon in the form of 

 grains. 



