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abundant albite altered rock andesite arsenopyrite barite beds biotite Bull calcite calcium California carbon dioxide cassiterite cent chalcocite chalcopyrite chlorite clay concentration contact-metamorphic contain copper deposits country rock crystalline crystals depth derived dikes district dolomite Econ epidote fault feet feldspar ferric fissures fluorite formation formed galena gangue minerals garnet Geology gold gold-bearing granite gravels hematite igneous rocks Inst intrusive iron kaolin Lake limestone limonite Lindgren lode magma magnetite mainly manganese masses metals metamorphism metasomatic mineral deposits mines Nevada nickel occur ore-bodies origin oxidation pegmatite phosphate places porphyry precipitated present probably production pyrite pyrrhotite quantities quartz veins quartzite rarely region replacement rich salt sandstone schists secondary sedimentary sediments sericite serpentine shale siderite silicates silver slates soluble solutions springs strata sulphate sulphides sulphuric acid surface Surv Survey temperature Tertiary tetrahedrite thick tion tourmaline Trans U. S. Geol usually volcanic zeolites zinc blende zone
Page ii - McGraw-Hill Book Company Electrical World The Engineering andMining Journal Engineering Record Engineering News Railway Age Gazette American Machinist Signal Engineer American Engineer Electric Railway Journal Coal Age Metallurgical and Chemical Engineering Power
Page 694 - A lode formation may be defined as a more or less vertical zone of rock, usually continuous with the surrounding rock and of similar origin, but distinct from it in carrying metallic ores disseminated through it in payable quantities and, as a rule, characterized by strong foliation.
Page 694 - can have free circulation. In consequence of this, mineral deposits are formed within the rock, usually but not necessarily extending over the whole of the foliated zone, but seldom beyond it, and having no definite boundaries horizontally or vertically other than those determined by the decrease of the assay value of the rock in any one direction.
Page 132 - The fault strike is the direction of the intersection of the fault surface, or the shear zone, with a horizontal plane. The fault dip is the inclination of the fault surface, or shear zone, measured from a horizontal plane.
Page 417 - their deposition taking place in the still hot rocks. That zeolitization is far from being simply an effect of the leaching by surface waters is shown by the absence of the zeolites from large areas of basic flows, many of them full of vacuoles or blowholes.
Page 131 - A fault is a fracture in the rock of the earth's crust, accompanied by a displacement of one side with respect to the other in a direction parallel with the fracture. The fracture is usually not an open crack, and an open crack would not be a fault unless one of the sides had moved parallel with the crack relatively to the other.
Page 24 - law of movable equilibrium states: When the temperature of a system in equilibrium is raised that reaction takes place which is accompanied by absorption of heat; and, conversely, when the temperature is lowered that reaction occurs which is accompanied by an evolution of
Page 809 - irregular bunches and masses along the contacts or in the interior of the intrusive masses; frequently also it forms illdefined streaks or "schlieren." In part the ore may have a secondary origin, being developed together with magnetite during the process of serpentinization from primary chromite, picotite,