WARREN COUNTY. 177 



polished specimen of which is in the Stale Collection. The serpentine in tliis quarry is dark 

 green, and imbedded in a ground of grey limestone. In Johnsburgh are two or three exten- 

 sive beds of the same material, but the color of the serpentine is yellowish green. 



It is ujmecessary to describe the diiferent varieties which liave been discovered. It is suf- 

 ficient to say that they are numerous, and that the color of the marble varies from a deep 

 green to a pale yellowish green. In general the stone is strong and sound ; and though in the 

 air, and exposed to the weather, it is subject to disintegration, yet when defended as it would 

 be when employed for mantel pieces and other ornamental work, it will have all the dm-ability 

 of gi'anite. 



The principal difficulty in fitting it for market, arises from the unequal hardness of the 

 materials composuig it. The serpentine is softer, and, in polishing, wears down more rapidly 

 than the limestone, and hence does not acquire that lustre which the limestone receives. 



Graphite, or Black Lead. 



It is a matter of some moment to discover a quantity of graphite sufficiently large to meet the 

 demands for it, and at the same time of a quality suitable to be employed for the finest drawing 

 pencils. A quantity was discovered in Jolmsburgh, on the farm of Mr. Noble, which it is 

 beheved possesses the quahlies required. It occurs in irregidar shaped masses, which are 

 finely laminated, and apparently of a good quality ; but it appears to be only in small quan- 

 tities. There was probably less than half a ton contained in the bed ; yet as it has not been 

 satisfactorily explored, it is impossible to speak with confidence. In this neighborhood, it is 

 largely distributed through the rocks ; and it is probable it may exist in beds or veins suffi- 

 ciently thick to be worth working. On the farm of Mr. Noble, it was in a mass of quartz 

 subordinate to limestone. In one of the unsettled townships, quite a large mass was disco- 

 vered of the finest quality. 



A beautiful form of this substance exists in Jolmsburgh ; it is in six-sided tables, and perfect 

 in form. The surfaces of these tables are marked by fine lines, indicating the rhomboid or 

 primary form to which the species belongs. These tables are disseminated in primary lime- 

 stone, and some are compound or twin crystals. This locality appears to be the only one 

 j-et discovered, which furnishes perfect crystalUne forms of this substance. 



Potsdam Sandstone. 



An outcrop of this rock may be observed about four and a half or five miles north of Glen's- 

 Falls. It appears as a hard quartz rock, dipping south and southwest. It rests upon gneiss : 

 no rock, therefore, intervenes between it and the primary. 



Again, under the same circumstances, at the eastern base of the Luzerne mountains, and 

 also on the west side, particularly at the High faUs at Corinth, this rock appears under its 

 usual characters. The latter place furnishes a fine opportunity for studying the gradual 

 change of rock from one form to another, when circumstances are favorable. At the falls, 



Geol. 2d Dist. 23 



