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areas argentiferous galena argentite Arizona arsenopyrite associated bornite breakdown brongniardite calcite cavities cent chalcocite chalcopyrite chalcopyrite cp cleavage Cobalt Cobalt district Colo covellite Cu2S described Econ Emmons Enrichment eral etching with nitric EXPLANATION OF PLATE fragments frequently galena gn galena Plate gangue gyrite hedrite huntilite hypogene illustrated in Plate investigation Irving and Bancroft late silver minerals later minerals later than galena Lyell marcasite material micro-chemical tests minerals of silver molecule Murdoch native silver niccolite nitric acid occurrence Ontario opaque minerals order of deposition paragenesis Plate XII Plate XVIII Plate XX polished specimen polished surfaces polybasite potassium cyanide proustite purplish pyrar pyrargyrite pyrite quartz reflecting microscope replacing tetrahedrite rich silver minerals ruby silver Sandon Shells of smaltite shown in Plate silver deposits Silver King smaltite smaltite sm so-called intergrowth solid solution sphalerite spots Spurr stephanite stromeyerite supergene Surv tetrahedrite tetrahedrite td Tonopah U. S. Geol
Page 333 - KNIGHT, CW (1906): A microscopic examination of the cobalt-nickel arsenides and silver deposits of Temiskaming — Econ. Geol., vol. 1, pp. 767-776. ELLSWORTH, HV (1916): A study of certain minerals from Cobalt, Ontario — Ann. Rep. Ontario Bur. Mines, vol. 25 (1), pp. 200-243. KEIL, K. (1929): Beitrage zur Kenntnis der Kobalt-Nickel-Wismut-Silber Erzgange — Diss., sachsischen Bergakademie — Freiberg.
Page 341 - The peculiar concentric structure seen in the cobalt-nickel minerals is believed to be due to the habit of the early mineral, smaltite, to replace calcite in the form of concentric shells. The later minerals replacing the remainder of the calcite inside the shells complete the structure. The spaces between the shells are sometimes filled (by replacement of calcite) with the earlier mineral smaltite, less often by the later mineral niccolite.
Page 306 - little of the argentiferous galena is rich in silver in any of these districts unless accompanied by tetrahedrite or some rich secondary silver mineral.
Page 341 - ... concentric shells. The later minerals replacing the remainder of the calcite inside the shells complete the structure. The spaces between the shells are sometimes filled (by replacement of calcite) with the early mineral smaltite, less often by the later mineral niccolite. 9. Micro-chemical tests applied on fragments secured from the polished surfaces are considered more useful in identifying silver minerals than the etching or tarnishing methods. 10. The order of deposition of the minerals in...
Page 336 - HNO3, etc. Argentite, polybasite and stephanite are put down as grayish white; silver, dyscrasite and huntilite as creamy white and proustite and pyrargyrite as bluish white. His etching and tarnishing tests are not characteristic and have been found of little value for purposes of identification. As stated in the introduction three important means have been employed for the identification of the silver minerals discussed . 66 Spurr, " Geology of the Aspen Mining District,
Page 304 - The geology and ore deposits of Iron Hill, Leadville, Colo.: Trans. Am. Inst. Min. Eng., vol. 18, 1890, p.
Page 341 - The writer is inclined to attribute greater activity in this respect to hypogene solutions than is general among economic mineralogists. This is due mainly to the fact that microscopic examination of mineral deposits shows a continuous series of replacements to have occurred and often there is no reason for considering those concerned with the deposition of the late silver minerals as different in kind from the earlier processes.
Page 331 - When associated with stromeyerite and other silver minerals it has sometimes been observed to show anomal6us features. In specimens from Silver King, Ariz., remnants were found showing unusual colors. On other residual grains this peculiarity appears as borders fading off almost imperceptibly into stromeyerite. It was at first thought that these effects might be due to solid solutions of stromeyerite and bornite, but on examination with high power the borders were proved to be non-homogeneous, but...
Page 338 - ... than to attempt making the test directly on the surface. Moreover by this method the specimen is much less damaged for further work. Having obtained the material in solution as outlined above, tests may be made for other elements according to the methods outlined by Chamot for general micro-chemical work.98 In the investigation of the cobalt-nickel minerals the 88 Chamot, " Elementary Chemical Microscopy,