a new Cornish Mineral. 57 



there is a second and more difficult cleavage parallel to the 

 faces of the form 10 0. 



The figures 1 and 2 represent the distribution of forms on 

 two crystals. 



H» I. 



Fig. 3 is a stereographic projection of the poles of the 

 crystal. 



Fig. 3. 



002. 



The optical character of the crystal is negative ; the acute 

 bisectors of the optic axes for different colours lie in the plane 

 of symmetry, and are very slightly inclined on the normal to 

 the face 1 0, the optic axes also lying in the plane of sym- 

 metry. 



