of Epistilbite and Heulandite. 



Fijr. 2. 



Ficr. 3. 



4/ d 



m '!'■ 



Fig. 4. 



M 



i M 



Fig. 4. represents the form of the crystals of Epistilbite, 

 and is a copy of the figure given in the Edinburgh Journal of 

 Science. The cleavage is parallel to a plane bisecting the 

 obtuse angle formed by the two planes M. The incidences of 

 the different planes of this figure given by Dr. Gustavus Rose 

 are the following : 



The primitive form I have adopted for Heulandite, in the 

 description of Mr. Turner's collection, is an oblique rhombic 

 prism represented fig. 1 ; the angles and dimensions -of 

 which are, 



m,m = 97" 39' P,m = lOS"" V b : h :: 1000 : 588 



the plane angle of the base is 92^ 22' 40", and that of the la- 

 teral faces 106' 24' 30". 



The 



