. De re metallica. Metallurgy; Mineral industries. 72 BOOK III. Lastly, the seams, which are the very finest stringers {fibrae), divide the rock, and occur sometimes frequently, sometimes rarely. From whatever direction the vein comes, its seams always turn their heads toward the hght in the same direction. But, while the seams usually run from one point of the compass to another immediately opposite it, as for instance, from east to west, if hard stringers divert them, it may happen that these very seams, which before were running from east to west, then contrariwise proceed from west to east
. De re metallica. Metallurgy; Mineral industries. 72 BOOK III. Lastly, the seams, which are the very finest stringers {fibrae), divide the rock, and occur sometimes frequently, sometimes rarely. From whatever direction the vein comes, its seams always turn their heads toward the hght in the same direction. But, while the seams usually run from one point of the compass to another immediately opposite it, as for instance, from east to west, if hard stringers divert them, it may happen that these very seams, which before were running from east to west, then contrariwise proceed from west to east, and the direction of the rocks is thus inverted. In such a case, the direction of the veins is judged, not by the direction of the seams which occur rarely, but by those which constantly A—Seams which proceed from the east. B—The inverse. Both veins or stringers may be solid or drusy, or barren of minerals, or pervious to water. Solid veins contain no water and very little air. The drusy veins rarely contain water ; they often contain air. Those which are barren of minerals often carry water. Solid veins and stringers con- sist sometimes of hard materials, sometimes of soft, and sometimes of a kind of medium between the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Agricola, Georg, 1494-1555; Hoover, Herbert, 1874-1964. New York, Dover Publications
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