317 



IVrnvskite, 273 



Retort, I-:. D., 159 



IVt/.itr, -, 90, 285 



IVwter ware, 185 



1'irsson, L. V., 165 



Pitchblende, 279 



1'lacrr ininiiiK, 84, 85, 86, 101 



Placers, 79, 80, 81 



ancient beach, 81 



associated minerals, 50, 57 



bench, 81 



creek, 80, 81 



deep lead, 50 



gravel-plain, 81 



gulch, 80 



hillside, 81 



residual, 80 



river-bar, 81 



sea-beach, 81 



shoad, 50 



sorted, 80 

 Platinum, 102 



alloys of, 105 



character of ore bodies, 102 



detrital, 50 



extraction of, 104 



geographical distribution, 103 



geological horizon, 103 



native, 102 



ores of, 102 



origin of ores, 102 



production of, 291 



properties of, 102 



uses of, 104 

 Platiniridium, 102 

 Pneumatolysis, 29, 30 

 Polianite, 246 

 Polybasite, 90 

 Polydimite, 238 

 Porcupine, Ontario, 83 

 Powellite, 269 

 Pratt, J. H., 219, 231 

 Precipitation, 41 

 causes of, 4 

 Proustite, 90 

 Psilomelane, 246 

 Pucherite, 276 

 Pyrargyrite, 90 

 Pyrite, 189 



Pyrochlore, 281 

 Pyrochroite, 246 

 Pyrolusite, 246 

 Pyromorphite, 110 

 Pyrrhotite, 189, 238 



Q 



Quartz, as gangue, 1 

 Quebec, Canada, 199, 230 

 Queluz, Brazil, 248 



R 



Rammelsbergite, 238 



Ransome, F. L., 69, 122 



Realgar, 164, 168 



Red lead, 125 



Reinite, 269 



Rhodium, 107 



Rhodochrosite, 246 



Rhodonite, 246 



Richthofen, F., 75 



Rickard, T. A., 80 



Rickardite, 285 



Ries, Heinrich, 69, 119, 128, 132, 

 142, 148, 152, 165, 179, 

 200, 224, 231, 242, 248, 250 



Robertson, J. D., 258 



Roscoelite, 276 



Ruby, 218, 222 



Russell, I. C., 201 



Ruthenium, 107 



Rutile, 272 



Safflorite, 235 



Samarskite, 281 



San Juan district, Colorado, 



Sapphire, 218 



Saucon Valley, Pennsylvania, 259 



Scheelite, 269 



Schmidt's law, 11 



Schrivenor, J. B., 183 



Secondary changes, 46 



Segregation, 25 



causes of, 26 



order of, 26 

 Selenium, 283 



character of ore bodies, 284 



