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Jersey Fire Clay Brick
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A highly siliceous clay brick, semisilica brick.
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Kaliphite
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A mixture of limonite with oxides of manganese and silicates of zinc and lime.
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Y Axis
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One of the three optic axes (x,y, and z) in a biaxial crystal. The y-axis is the intermediate optic axis, at right angles to the plane containing optic axes x and z. Light vibrating parallel to the y-axis is called the intermediate ray, the y-ray, and the beta -ray. The middle-value index of refraction nbeta in biaxial minerals is the index of the intermediate ray vibrating parallel to the y-axis.
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A Horizon
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Soil zone immediately below surface, from which soluble material and fine-grained particles have been moved downward by water seeping into soil. Varying amounts of organic matter give A horizon color ranging from gray to black.
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Aa Channel
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A narrow, sinuous channel in which a lava river moves downward and away from a central vent or fissure to feed an aa flow. At the end of eruptive activity, the lava river ordinarily drains away, leaving an open channel mostly floored with spinose aa.
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Aa Lava
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Lava whose surface is covered with random masses of angular jagged blocks.
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Abandoned Workings
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Excavations, either caved or sealed, that are deserted and in which further mining is not intended and open workings that are not ventilated and inspected regularly. Syn: abandoned mine Federal Mine Safety
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Abbe Jar
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In mineral processing, a porcelain jar used for laboratory batch grinding tests in ceramic ware.
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Abbe Theory
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The visibility of an object under the microscope is directly proportional to the wavelength of light, and inversely to the aperture of lens.
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ABC System
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A method of seismic surveying by which the effect of irregular weathering thickness may be determined by a simple calculation from reciprocal placement of shotholes and seismometers. The method was originally used to solve refraction problems arising from irregularities in the top of the high-velocity layer.
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