TABLE OF CONTENTS. XV 



Evidences of the progressive formation of such v;- ins .... 198 



Rare minerals in the granitic vein-stones of New England . . . 200 



Geodes in granites in New Brunswick and Italy ..... 201 



Granitic veins distinguished from dikes 202 



Volger and Fournet on the filling of granite veins 202 



Recent age of some concretionary veins . . . . . 203 



Note on the salt-wells of Goderich in Ontario 204 



On the conditions of the crystallization of quartz . . . . . 205 



On the emerald-bearing veins of New Grenada 205 



Recent production of crystalline zeolites 205 



The Laurentian series; its lithological characters 206 



Vein-stones in the Laurentian rocks 208 



These vein-stones compared with those of Scandinavia .... 209 



Minerals of the Laui'entian vein-stones ....... 210 



Note on the occurrence of leucite 210 



The concretionary character of these vein-stones shown . . . 211 



Incrustation and skeleton-crystals described ...... 211 



Crystals with rounded angles ; their significance 212 



Feklspathic veins of the Laurentian rocks 214 



Complex nature of the Laurentian vein-stones 215 



Vein-stones with apatite and with graphite ...... 216 



Paragenesis of their mineral specie* 216 



Concretionary copper-bearing veins of the Blue Ridge .... 217 



Supposed eruptive origin of crystalline limestones .... 218 



XII. 



THE ORIGIN OF METALLIFEROUS DEPOSITS. 



Preliminary statement of the theory of ore-deposits 220 



Distribution and diffusion of the chemical elements .... 221 



Separation and concentration of certain elements 222 



Note on the solvent powers of water ....... 223 



The terrestrial circulation compared with that of animals . . . 224 



History of the diffusion and concentration of phosphates . . . 225 



Potash and iodine ; their elimination from sea-water .... 226 



Intervention of organic life in all these processes 226 



History of the diffusion and the concentration of iron . . . .227 



Relation of iron-oxides to ancient vegetation 229 



Formation of iron-pyrites and other sulphides 230 



Diffusion of copper, silver, and lead in the ocean ..... 231 



Reduction of copper from its solutions 232 



Ore-deposits in beds and in fissures 233 



The process of deposition in veins 234 



Uniformity of operations in nature 235 



APPENDIX. 



Sonstadt on the iodine in sea-water 237 



On gold in the ocean ; Sonstadt and Henry Wurtz .... 237 



