CONTENTS. XXI 



IV. OF THE IMPERFECTIONS OF CRYSTALS IN RESPECT TO 

 THEIR FOHM. 



, 158. Two kinds of this Imperfection . 209 



. 159. Deviations from Regularity, depending upon the 



Formation of the Individuals themselves 210 



. 160. Deviations from Regularity, depending upon the 



Contact with other Individuals . 216 



CHAPTER II. 



Of the Structure of Minerals. 



. 161. Explanation of Structure . . 219 



. 162. Cleavage . . .221 



. 163. Faces of Cleavage . . 221 



. 164. Direction of Cleavage . . 222 



. 165. Character of Cleavage . . 223 



. 166. Faces of Cleavage parallel to Faces of Crystalli- 

 sation . . . 224 

 . 167. Form of Cleavage . . 225 

 . 168. Forms of Cleavage, distinguished according to 



the quality of their Faces . . 227 



. 169. Forms of Cleavage Members of the Series of 



Crystallisation . . 229 



. 170. Designation and Nomenclature of the Forms of 



Cleavage . . .231 



.171. Fracture ... 232 



. 172. Faces of Fracture . . ,233 



. 173. Character of Fracture . . 234 



k CHAPTER III. 



Of Surface. 



. 174. Surface in general . . .235 



. 175. Striated Faces of Crystallisation . 236 



. 176. Diverse qualities of the Faces of Crystallisation 238 

 . 177. Faces of Composition . , 240 



