Economic Geology, Band 2Economic Geology Publishing Company, 1907 |
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acid altered alunite amount analyses apatite associated Bain beds belt biotite blue calcite carbon cent chalcocite chalcopyrite chemical chlorite clay coal color concentration contains copper Copperopolis country rock County crystals dacite deposits depth dikes district dolomite east ECONOMIC GEOLOGY emanations fault plane feet feldspar field fissures formation fracture Geol geologists gold grains granite granodiorite horizontal hornblende hornblendite igneous rocks inches intrusive iron kaolin later lead and zinc lignite limestone magma magnetite mass material metals metamorphic metasomatic miles minerals Mining Mountain movement occur origin outcrops oxidation peat pegmatites pentlandite plates porphyry portion present probably produced Professor pyrite pyrrhotite quartz region rutile samples sandstone schist sediments sericite serpentine shale silicate slates solutions structure sulphides sulphur surface thickness tion turquoise U. S. Geological Survey valley veins vertical wall zone
Beliebte Passagen
Seite 74 - A body of mineral or mineral-bearing rock in the general mass of the mountain, so far as it may continue unbroken and without interruption, may be regarded as a lode, whatever the boundaries may be. In the existence of such a body, and to the extent of it, boundaries are implied.
Seite 139 - ... over 90 per cent of the sedimentary material. These pelagic or floating algae fell in prolonged showers in quiet or protected areas where the water was presumably somewhat charged with tannic or humic solutions conducive to the early arrest of anaerobic bacterial decomposition. Possibly the bacterial action was arrested by its own products. The original deposits were doubtless several times as thick as those now remaining, since it is probable that the organic residue represents as little as...
Seite 56 - ... of such a size as to yield at least 5 pounds of coal per foot of thickness of coal bed — that is, 5 pounds for a bed 1 foot thick, 10 pounds for a bed 2 feet thick, 20 pounds for a bed 4 feet thick, etc. 4. All material encountered in such a cut should be included in the sample, except partings or binders more than three-eighths inch in thickness and lenses or concretions of sulphur...
Seite 56 - ... 4. All material encountered in such a cut should be included in the sample, except partings or binders more than three-eighths inch in thickness and lenses or concretions of " sulphur " or other impurities greater than 2 inches in maximum diameter and one-half inch in thickness. 5. If the sample is wet, it should be taken out of the mine and dried until all sensible moisture has been driven off. 6. If the coal is not visibly moist, it should be pulverized and quartered down inside the mine to...
Seite 619 - As the alga; matter became compressed the beds above broke and settled, leaving open spaces of peculiar form for the ultimate reception of the ore bodies. The beds were slightly deformed, whereby the basins were accentuated and deep joint cracks were developed. The area was subjected to peneplanation and later to gorge cutting, whereby the overlying shale was cut away and a vigorous underground circulation was brought about. This circulation resulted in a concentration of the disseminated material,...
Seite 74 - To determine whether a lode or vein exists it is necessary to define those terms ; and, as to that, it is enough to say that a lode or vein is a body of mineral, or mineralbearing rock, within defined boundaries in the general mass of the mountain. In this definition the elements are the body of mineral or mineral-bearing rock and the boundaries; with either of these things well established very slight evidence may be accepted as to the existence of the other. A body of mineral or mineral-bearing...
Seite 139 - ... gram and in the alkaline .0012 gram. If even now this material has such a prompt reducing action it may well be supposed that when first formed this action was much more important. That the oil rock has suffered loss of a large amount of its volatile matter is indicated by phenomena already discussed. The small interbanded layers of limestone have been broken and brecciated and in places the oil rock becomes almost a breccia in appearance, with slickensided surfaces indicating movement of the...
Seite 76 - The King, convinced of the deteriorated condition in which the important branch of mining of that kingdom has fallen, from a want of method in governing the Reales of mines, and also on account of the frequent and troublesome litigations in which the individuals of this useful profession are involved, causing them enormous expense and distraction from their business by requiring them to reside in the capital and other places where they go in the prosecution of their lawsuits, etc.
Seite 136 - Local abundance of organic matter. — It is to the local occurrence of organic deposits that Whitney and Chamberlin have appealed for an explanation of the localization of the ores. Whitney evidently had in mind the organic matter due to the decay of animals such as form the ordinary fossils found in the rocks, though the agency of long branching sea weeds was also called into requisition." The notion that abundant animal life first appeared about the time those deposits were formed, causing the...
Seite 120 - ... referred to the mineral as characteristic of certain classes of veins, kaolinite should not be considered as a gangue mineral of any class of ore deposits except those formed under the influence of oxidation. In a subsequent paragraph he somewhat modified this statement by the expression of belief that " kaolin is rarely formed by alkaline hot water at any considerable depth below the surface.