Bulletin - United States Geological Survey, Ausgabe 229

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Seite 56 - ROLKER, CM The production of tin in various parts of the world. In Sixteenth Ann. Rept., pt. 3, pp. 458-538. 1895. ULKE, T. Occurrence of tin ore in North Carolina and Virginia.
Seite 35 - 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 47 - ... penetrated 140 feet vertically without reaching the bottom. In the mountains near its source the ore is angular and in comparatively large fragments, sometimes from an inch to a foot or more in diameter.
Seite 20 - The individual lesions appear as tense, clear, shiny vesicles, obtuse, round, or ovoid in form, and varying in size from that of a pin head to that of a pea.
Seite 36 - The determination of percentage by weight was as follows: 90 per cent tin-stone; 5 per cent magnetite; other minerals, 5 per cent. The cassiterite occurs in grains and pebbles, from those microscopic in size to those half an inch in diameter; they have subrounded and rounded forms. In some cases there is a suggestion of pyramidal and prismatic crystal forms. The cassiterite varies in color from a light brown to a lustrous black. A second locality of this mineral was found on the Anikovik River about...
Seite 45 - Maine a' cassiterite occurs at Winslow in small veins, which traverse impure limestone, with purple fluorite, mica, quartz, and mispickel. These veins have been prospected to a depth of 100 feet, but have yielded no tin in commercial quantities. Similar occurrences are reported at Paris and Hebron. In Massachusetts a few crystals of cassiterite have been found with albite and tourmaline at Goshen and Chesterfield. In Missouri* a small amount of cassiterite has been found replacing sphene in granite....
Seite 35 - In some cases, however, a little plagioclase was still unaltered and a suggestion of ophitic structure remained, so that these are probably of a diabasic character. The slates and schists are everywhere penetrated by small veins, consisting usually of quartz with some calcite, and frequently carrying pyrite and sometimes gold. These veins, are very irregular, often widening out to form blebs, and again contracting so as not to be easily traceable.
Seite 45 - Jackson in 1840 by Doctor Jackson. It occurs with arsenical and copper pyrites, fluorspar, and phosphate of iron in small quartz veins, and mica, slate, and granite near a trap dike. In South Dakota'' the Black Hills contain noteworthy deposits of tin ore, which, however, have not yet proved commercially productive. They occur in an area of coarse-grained granite in the central part of the hills. The Etta mine deposit, the only one that has produced any considerable quantity of tin, is a lenticular...

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