Notices of Trappean Minerals. 



57 



works. (Yide Shepard, Yol. II, p. 37.) Most of them in my 

 specimens are quite small, although very distinct. My largest 

 crystal is a little more than a quarter of an inch in diameter. 



Mesotype. — I introduce this mineral here because it is apt to 

 be mistaken for the preceding, with which it is often associated. 

 As there is some confusion in regard to this species, it may be 

 proper for me to state that this notice applies to the mineral call- 

 ed mesolite by Dr. Thomson and others, which I have observed 

 only in the gneiss of Harlem, although according to Mr. Bourne, 

 it has been found quite abundantly at Bergen. 



The mineral to which I refer, occurs in very minute but highly 

 finished transparent crystals. The prisms appear to be rectangu- 

 lar, but on inspection they will be found to be slightly rhombic. 

 The terminations, which are usually four-sided, are variously 

 modified, as in the annexed figures. All these forms result from 

 the different degrees of extension of the planes o. 



Fig. 1. Fig. 2. 



Harlem, N. Y. 



I M 



Harlem, N. Y. 



M 



Fig. 3. 



M 



M 



MonM, 91° 20' 



Mon o, 116° 32', Hauy. 



116° 58', Phillips, 



Harlem, N. Y. 



Analcime. — This mineral occurs in small crystals of the leu- 

 cite form at Bergen Hill, where it is associated with stellite, 

 datholite, &c. It has long been credited to Paterson, N. J. I 

 have also found crystals of the same form in the gneiss near 

 Yonkers, in Westchester county, N. Y. The crystals are often 

 Vol. xliv, No. 1.— Oct.-Dec. 1842. 8 



