TIM-: ORTHORHOMBIC SYSTEM 



11.1 



II. Prisms, nfi : b : oo c ; (hko). 



Prisms :uv parallel to the c axis; the poles of Fig. 217 will lie 

 on the primitive circle between the cligonal axes. When the pole 

 is nearer & the form will be of the 

 macro series, & : nb : ooc, as its in- 

 tercept on b will be larger than 

 unity, and when near b, the form 

 will l)e of the brachy series; Fig. 221 

 is the unit prism, which is the limit- 

 ing form connecting the two series. 



III. Domes. Macro series of 

 domes, nft : oo b : me ; (hok). 



When the poles lie in the diam- 

 etral plane containing the c and 

 & axes, the faces will be parallel to 

 the macro axis, and the form will 

 be a macrodome Fig. 222, an open 

 form bounded by four similar faces. 

 There will be a series of macrodomes 

 the angles of which and the inter- 

 cepts on the axes will depend upon 



FIG. 221. The Unit Prism of Bante. 



the position of the poles. 



Brachy series of domes, oofi: nb : me; (ohk). 

 When the poles lie in the plane of symmetry containing the c 



if- 



FIG. 222. The Unit Macro- 

 dome of Barite. 



FIG. 223. The Brachy Scries of Domes. 



and b axes, the faces will be parallel to the brachyaxis, and the 

 form will be a brachydome, of which there is also a series, Fig. 

 223. 



