Sust. FEM. Sedimentary rock composed of clay and silt deposits. Porous, permeable little, is due to insufficient communication between holes, often rolled thin, fissile, layers of varied shades of colors: black, grey, bluish, yellowish, whitish, reddish, greenish grey. The very dark contains abundant organic matter. It is called bituminous shale. It may contain oil and natural gas ( lutigas ) in usable quantities. By metamorphism becomes in Slate and phyllite. Its name derives from the latin «lutum»: mud, mud, silt, mud, silt, and 'ita' suffix: common rocks and minerals.
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