Kiefer, Nigredo, 1984
Oil, acrylic, emulsion, shellac, and straw
on photograph, mounted on canvas, with woodcut
130 x 218 1/2 in. (330 x 555 cm)
Philadelphia Museum of Art

from : http://www.artchive.com/artchive/K/kiefer/nigredo.jpg.html

“Nigredo” is the first plateau of achievement in the alchemical process or “magnum opus”, by which the alchemist seeks to transmute the ordinary – that is, to turn base matter such as lead, earth or stone into gold.