226 



DESCRIPTIVE MINERALOGY. 



Fig. 97. 



Fig. 98. 



^'*- *^' At the Natural dam, about two miles from the village of 



Gouvemeur, loose crystals of rarious sizes occur in a de- 

 composed rock. Some of these are very large, but they are 

 usually from half an inch to two inches in length. Many of 

 them are single rhombohedrons with the contiguous acute 

 edges replaced by broad tangent planes. Fig. 96. F ong 

 about 143°. In some cases, three or four of the sides are 

 similarly replaced. Two, three or more crystals are often 

 grouped together by the opposite faces, presenting an imbri- 

 cated appearance. Figs. 97 and 98 represent twin crystals 

 which I have found at this locality, and the arrangement of 

 which will be easily understood. It may be observed that 



the colour of the calcareous 

 from the Natural dam is of- 

 ten brown, and the surfaces 

 of cleavage are bent like 

 pearl spar. But here as at 

 Oxbow in Jefferson, this va- 

 riety constantly passes into 

 the white, transparent and 

 opaque kinds. They are 

 probably all pure, or nearly 

 pure carbonate of lime. 

 In the town of Rossie, about a mile southeast of Oxbow in Jefferson county, there is a loca- 

 lity not unlike that on the farm of Dr. Benton (see page 218). The crystals are similar in form, 

 and are also found in a decomposed limestone. Transparent cleavages of considerable beauty 

 have been obtained here, as well as those which are white and opaque, brown, yellow, rose and 

 purple. Crystals of three or four inches in length occur, which are doubly terminated. Many 

 of them are peculiar in having a white opaque coating on the surface, and some of them appear 

 to have undergone a kind of dissection or solution, the whole exterior being studded with sec- 

 tions of minute crystals. The appearance is not unlike that which is observed when an amor- 

 phous mass of alum is allowed to remain for some time in water. The 

 most interesting crystalline form that I have observed here, is a compound 

 one represented in Fig. 99. As in some of the crystals from Lockport, 

 six of the edges are not well defined, the principal faces being only a little 

 rounded. 



At the Parish ore bed in Gouvemeur, geodes of calcareous spar are 

 found in the specular iron ore ; some of which possess considerable beauty. 

 The forms are the primary and the dodecaedre of Haiiy (Fig. 71). 



To the above localities, I may add the bank of Laidtaw lake, Rossie, 

 where loose crystals have been found ; and the town of Russel, where it 

 is said to be of a reddish colour. 



