Contributions to Economic Geology, 1902

U.S. Government Printing Office, 1903 - 449 Seiten

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Seite 453 - 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 90 - Reconnaissances in the Cape Nome and Norton Bay regions, Alaska, in 1900,
Seite 89 - In general it may be said that all the veins of the district carry rich ores in bonanzas and ore shoots within the first 200 feet from the surface, but that in depth the ores rapidly decrease in value until the vein is no longer workable. It may also be said that the ore shoots were well defined, and the intervening vein matter barren and unworkable. The pitch of the ore shoots conforms to the usual habit, dipping to the right when looking down the dip of the vein. The ores consist of sulphides and...
Seite 92 - Creek 2 to 3 feet of gravel overlies the bed rock, which consists of arenaceous schists, often graphitic, together with some graphitic slates. This is part of the schist series which has been described. The bed rock is much jointed, the schists being broken up into pencil-shaped fragments. They strike nearly at right angles to the course of the stream and offer natural riffles for the concentration of heavier material. A hasty reconnaissance of the drainage basin of this stream, which includes not...
Seite 176 - Weed,5 in masses of nearly pure leadlike mineral 20 feet or more wide. In depth the mineral shows a more crystalline structure, and it is found in all the mines in greater or less abundance and purity, but in the great bulk of the ores it forms small grains scattered through the ores. Emmons, Weed, Tower, and many others who studied the copper lodes in the earlier stages of their development regarded the chalcocite ores as secondary deposits formed by descending waters.
Seite 171 - S,(KMI tons of oxidized silver ore, from the Anaconda ledge, was treated in this mill, yielding about 30 ounces of silver to the ton. The ore contained just enough copper to make it unnecessary to add bluest/one in the raw amalgamation, but the resulting bullion was very base, sometimes running only 400 fine. In working the vein a drift running northeast at, a depth of 100 feet ran into a seam of copper glance a few inches wide.
Seite 178 - Country Rock. — There is a distinct association of the copper deposits with the Modoc porphyry occurrence, since the most productive lodes occur in the area penetrated by this rock. The veins cross the porphyry, however, even the earliest ones, and hence the vein fractures are of later occurrence. There is also a distinct genetic relation between ore and country rock, as a result of the deposition of the ore by metasomatic replacement.
Seite 29 - ... very slowly, indefinitely, almost imperceptibly at first, the new poetry arose. For a new poetry it was, although, until the time of Burns, it was, to a large degree, held in check by the dominant authority of the other school. The course of this movement in the history of eighteenth-century letters may be indicated by a brief mention of some of the more important poets concerned. The first to attain to any prominence was a Scotchman, JAMES THOMSON (1700-1748). Of him Saintsbury says in his History...
Seite 428 - ... feel", and containing enough ocher to soil the fingers. In the next phase the ocher preponderates, but is held together by a more or less continuous skeleton of silica, although it can be readily removed with a pick. The final stage in the transition is the soft yellow ocher, filling the veins, which crumbles on drying, and contains only a small proportion of silica in the form of sand-grains. "The intermediate zone between the pure ocher and the quartzite is usually a few inches in thickness,...
Seite 172 - ... cents per pound. In silver the ore carried not less than $50 per ton, but the works charged a high price for treatment, owing to the presence of arsenic, which made the metal brittle. Soon after the erection of the Colorado Smelter the Parrot, Montana Copper, Clark's Colusa, and the Bell Company began smelting operations. The matte produced by these works was shipped to Eastern markets for refining. In 1884 the Anaconda Smelter...

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