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 NATURAL ABRASIVES 267 Economic features 267 Geologic features 269 ASBESTOS 270 Economic features 270 Geologic features 271 BARITE (BARYTES) 272 Economic features 272 Geologic features 273 BORAX 274 Economic features 274 Geologic features 275 BROMINE 277 Economic features 277 Geologic features 278 FULLER'S EARTH 278 Economic features 278 Geologic features 279 GRAPHITE (PLUMBAGO) 279 Economic features 279 Geologic features 282 GYPSUM 283 Economic features 283 Geologic features 284 MICA 285 Economic features 285 Geologic features 287