200 



PHYSIOGRAPHY. 



Feldspar. 



viduals, will be formed, which are nearly rectangular, and 

 bounded on their extremities by the faces P P and x x. 

 This composition is seen in the annexed figure. 



Fig. 191. 



It is a frequent form, from St. Gothard. 



2. Two crystals, like Fig. 187, excepting planes x and 

 s. Axis of revolution parallel to the principal axis, face of 

 composition parallel either to the right (Fig. 192.) or to the 

 left faces (Fig. J93.)ofM. 



Both are found near Elbogen in Bohemia. 



3. Axes of revolution perpendicular, face of composi- 

 tion parallel to P, angle of revolution =180. 



