1846.] Mineral Resources of JYew York. 31 



valley the gneiss, for the most part, is so irregularly ledded that 

 few if any quarries of this rock are known which are susceptible 

 of being wrought into good flagging stone or other works of con- 

 struction. 



The only rock of this northern district which may at some fu- 

 ture time be turned to a valuable account, is the hypersthene rock 

 of the interior of Essex county. This rock consists of Labrado- 

 rite, a handsome variety of feldspar, the finest colored varieties of 

 which are smoke gray of various tints. This rock is susceptible 

 of a fine polish, and for the more expensive and beautiful orna- 

 ments for parlors, is extremely well adapted. It is sufficiently 

 hard to resist all ordinary instruments which are in use, and hence, 

 would retain its polish and lustre as long as most of the gems. 

 Hardly any thing can exceed the beauty of this stone for mantle 

 pieces, centre tables, or any other piece of furniture for the parlor. 

 We are well aware that the expense of dressing and polishing it 

 will be considerable; still we believe that, by suitable machinery, 

 it may be prepared for use at a price which shall not carry it be- 

 yond the means of our men of wealth and fashion. We, however, 

 can only speak of this material as one which may probably be 

 turned to good account hereafter, or, as one which will furnish a 

 field for labor, and a probable return of profit to ingenious and 

 skilful workmen. 



The primary limestones. It is necessary to keep up the distinc- 

 tion of the limestones found associated with the granites, and oc- 

 casionally with gneiss and hornblende, and those which occur in 

 the taconic system. They may frequently be knowm, even in 

 hard specimens, the former being distinguished by their contain- 

 ing graphite and other minerals which are usually associated with 

 primary rocks. This limestone occurs in veins in granite in beds 

 beneath it, and in irregular masses in hornblende and gneiss; 

 sometimes apparently in beds parallel to those of the rock with 

 which it is associated. It is usually magnesian, and is not so well 

 adapted for quicklime, or for a furnace flux in smelting ores, as the 

 pure carbonate of lime ; neither is it suitable for marble, on account 

 of its coarse grain and imbedded simple minerals which it so fre- 



