Sulphate, of Lime. 



231 



new red sandstone at the falls. Some of the iron-colored grains are 

 not magnetic enough to be taken up by the magnet, and resemble 

 iserine. 



Rotten Stone. 



This valuable substance cannot probably be regarded as a simple 

 mineral, since in the present case, it is merely fetid limestone that has 

 been partially decomposed by the action of a mass of greenstone in 

 the immediate vicinity ; or by some other cause. It is found at Paine's 

 quarry in West Springfield ; and in large quantities. Its quality ap- 

 pears to be very excellent ; and in an economical point of view, it 

 deserves attention. It is found also at South Hadley Canal, on the 

 West Springfield shore ; though of hardly so fine a quality, and in 

 much less quantity. It is not there associated with limestone. (Nos. 

 217 to 221.) 



Fibrous Limestone, or Satin Spar. 



The red and black shales, as remarked in another place, on the 

 banks of Westfield river, in West Springfield, contain numerous 

 veins of this substance from an inch to a mere line wide. Sometimes 

 it forms a thin seam between the layers of slate. The same mine- 

 ral occurs along with the fish impressions at Sunderland. Common 

 calcareous spar exists in these rocks as well as satin spar. 



Concreted carbonate of lime is frequently found in this formation. 

 At West Springfield I found it an inch or two thick between the lay- 

 ers of sandstone, near the southern bed of fetid limestone. At the 

 Sunderland cave, it forms small and imperfect stalactites on the coarse 

 conglomerate : and on the same conglomerate, on the east side of 

 Mount Toby in Leverett, I found a large quantity of it coating over 

 a perpendicular wall several inches thick. (Nos. 226 to 230.) 

 This had obviously been derived from the conglomerate by water ; 

 and it shows that carbonate of lime is more frequent in this forma- 

 tion than one would be led to suspect from its general appearance. 



Sulphate of Baryta. 



This mineral, as already remarked, accompanies the veins of cop- 

 per ore in the new red sandstone in most instances, both in Massa- 

 chusetts and Connecticut. In this State, it is most abundant at the 

 copper veins in Greenfield ; where it forms veins from six to eight 

 inches wide. 



