" We were fascinated by the little glass spheres, by those dark waves of color, some narrow and drawn out into several swirls, and others that widened out in the center of the marble into a single bundle and thinned out smoothly at the ends. There were reddish streaks in Añuco's new marbles, but in the cloudy, chipped ones the bands of color also appeared, strangely and inexplicably. "

― Rafael Alberti , Antología poética