146 



faces of the octaedral formation, and the right-angled ones 

 of the cube formation, may meet opposite, as at the right 

 fiand figure, or alternate, as on the left hand figure. 



The upper figure is from a specimen in the Marchioness 

 of Bath's cabinet, and contains most of these modifica- 

 tions. The lower one is from a specimen in my own col- 

 lection. They both came from Derbyshire some time since, 

 and are the only British ones we know of. 



