slicken (slikn)

[ Grey incoherent clay, slickensided , and with many rhizomes and roots of Psilophyton. Dawson, Geol. Hist. Plants, p. 105. slickensides (slik'n-sīdz), n. pl . [ slicken + sides , pl. of sidel .] In mining , polished and striated surfaces of the rock, often seen on the walls of fi ure-veins, and the result of motion, under immense pre ure, of parts of the country-rock, or of the ma of the vein itself. Well developed slickensides are most frequently seen in connection with mineral veins, but the sides of joints in non metalliferous rocks occasionally exhibit this kind of striation. Slickensided surfaces are frequently coated with a thin film of pyrites, galena, hematite, or some other mineral, which may be polished so as to reflect the light like a mirror (whence the French name miroirs ). Nearly akin to this jointed character are the slicken sides , or polished and striated surfaces, which, sometimes of iron pyrites, but more usually of copper pyrites, often cover the faces of the walls of lodes. Henwood, Metalliferous Deposits of Cornwall and Devon, [p. 181.