Professional Paper - United States Geological Survey

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Seite 373 - ... the total number issued is large. They have therefore been classified into the following series: A, Economic geology; B, Descriptive geology; C, Systematic geology and paleontology; D, Petrography and mineralogy; E, Chemistry and physics; F, Geography; G, Miscellaneous; H, Forestry; I, Irrigation; J, Water storage; K, Pumping water; L, Quality of water; M, General hydrographic investigations; N, Water power; O, Underground waters; P, Hydrographic progress reports.
Seite 377 - SLIPS. [Mount each slip upon a separate card, placing the subject at the top of the second slip. The name of the series should not be repeated on the series card, but the additional numbers should be added, as received, to the first entry.] Gannett, Henry.
Seite 156 - The reason for the decrease in assay values of copper along certain open and water-bearing fracture zones is doubtless to be found in the wellknown fact that under the action of surface waters copper suffers rapid alteration and transportation. It appears then that in the disseminated ores in igneous rock the copper...
Seite 109 - ... ore deposits is marked by those in the Zelnora (elevation 8,375) " and the lowest levels in the Brooklyn (elevation 5,875) and Dalton and Lark (elevation 5,810). Ore bodies are thus known through a vertical range of approximately 2,565 feet. GEOLOGICAL DISTRIBUTION. Character of country rock. — The sedimentary section exposed in this district embraces several thousand feet of massive quartzite, thin, intercalated limestones, and calcareous shales. Though the calcareous members form a very small...
Seite 177 - ... Boy, exhibit the same massive bedded structure. This selective action leads to a very irregular periphery. The transition from massive, solid ore to barren country on the periphery is not sharp, as in the case of the lodes, where the transition from the rich bands to barren wall rock is well defined. On the contrary, it is gradual, passing from the bed of rich copper sulphide through lean copper ore, still poorer ore, merely stained country, to normal, barren, marble country. Although the composition...
Seite 177 - As was stated in the description of the structure of the copper shoots (p. 155), the broad characteristic of this structure is banding. This banding is not like the crustified or even the roughly banded structure of the lodes, but is a bedding which in form is identical with the bedding of strata. The chief difference is in composition, these beds being composed of ore instead of limestone or quartzite. Bedded structure characterizes alike miniature ore bodies, mineralized wall rock adjacent to seams,...
Seite 210 - Penrose, RAF, Jr., Jour. Geol., 1894, p. 296. tion may extend. Sulphide enrichment is of this character, for ' ' while this redeposition in many cases appears to commence at or near the ground-water level, it does not appear to have a necessary connection with that level, and may under favorable conditions extend below that level for a distance as yet undetermined." . . ." Recent chemical and physical investigations tend to extend this distance, and it is coming to be recognized that this zone of...
Seite 290 - There are five or six ore pipes in the length of ground broken, dipping in the vein from the southwest 45°. One-fifth of the vein on its strike is ore pipes. " * " One shoot was found from 20 to 60 feet long, and 5 to 25 feet (average, 7 feet) wide, extending rom the surface to a depth of 500 feet. Another body of very clean carbonate ore began 160 feet from the surface and extended 100 feet, being 6 feet wide and 50 feet long. Various other small beds have been found.
Seite 177 - Further, the marked deposition of ore along certain beds, and the slight deposition along others, appear to indicate a selective tendency on the part of mineral in solution for more soluble beds. Similarly, in small shoots the massive structure is a bedding of massive ore which is more extensive in some beds than in others. Finally, the immense lenses of cupriferous pyrite, eg, those in the Highland Boy, exhibit the same massive bedded structure. This selective action leads to a very irregular periphery....
Seite 205 - X, pp. 24—25. 1900. Secondary Enrichment of Ore Deposits. Trans. Am. Inst. Mg. Eng'rs. Vol. XXX, pp. 177-217. Ibid., Genesis of Ore Deposits (1902), pp. 199-204, 433-473, 756-762. 1900. Review of Kemp's Ore Deposits of the United States. Science, ns Vol.

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