Rŏck'-sōap, n.
n. (Min.) A mineral having a smooth, greasy feel, and adhering to the tongue. It is composed chiefly of silica, alumina, and water, with sometimes a small proportion of oxide of iron. Dana.
n. (Min.) A mineral having a smooth, greasy feel, and adhering to the tongue. It is composed chiefly of silica, alumina, and water, with sometimes a small proportion of oxide of iron. Dana.