GEOLOGIC FEATURES 166 Sedimentary iron ores 166 Iron ores associated with igneous rocks 171 Iron ores due to weathering of igneous rocks 171 Iron ores due to weathering of sulphide ores 173
MANGANESE ORES 173 Economic features 173 Geologic features 176
CHROME (OR CHROMITE) ORES 178 Economic features 178 Geologic features 179
NICKEL ORES 180 Economic features 180 Geologic features 181
TUNGSTEN (WOLFRAM) ORES 182 Economic features 182 Geologic features 184
MOLYBDENUM ORES 185 Economic features 185 Geologic features 186
VANADIUM ORES 187 Economic features 187 Geologic features 188
ZIRCONIUM ORES 189 Economic features 189 Geologic features 189
TITANIUM ORES 190 Economic features 190 Geologic features 190
MAGNESITE 191 Economic features 191 Geologic features 192
FLUORSPAR 193 Economic features 193 Geologic features 194
SILICA 195 Economic features 195 Geologic features 196
CHAPTER X. COPPER, LEAD AND ZINC MINERALS 197
COPPER ORES 197 Economic features 197 Geologic features 199 Copper deposits associated with igneous flows 200 Copper veins in igneous rocks 201 "Porphyry coppers" 203 Copper in limestone near igneous contacts 204 Copper deposits in schists 204 Sedimentary copper deposits 205 General comments 206
LEAD ORES 209 Economic features 209 Geologic features 211
ZINC ORES 213 Economic features 213 Geologic features 216
CHAPTER XI. GOLD, SILVER, AND PLATINUM MINERALS 221
GOLD ORES 221 Economic features 221 Geologic features 226
SILVER ORES 231 Economic features 231 Geologic features 234
PLATINUM ORES 237 Economic features 237 Geologic features 239
CHAPTER XII. MISCELLANEOUS METALLIC MINERALS 241
ALUMINUM ORES 241 Economic features 241 Geologic features 243
ANTIMONY ORES 246 Economic features 246 Geologic features 248
ARSENIC ORES 249 Economic features 249 Geologic features 251
BISMUTH ORES 252 Economic features 252 Geologic features 252
CADMIUM ORES 253 Economic features 253 Geologic features 254
COBALT ORES 254 Economic features 254 Geologic features 255
MERCURY (QUICKSILVER) ORES 255 Economic features 255 Geologic features 258
TIN ORES 260 Economic features 260 Geologic features 261
URANIUM AND RADIUM ORES 263 Economic features 263 Geologic features 264
CHAPTER XIII. MISCELLANEOUS NON-METALLIC MINERALS 267
