The proposed sculpture is an iron and granite representation of a sekimori-ishi. A sekimori-ishi is a stone tied with garden twine, placed on a path in a Japanese garden as a request not to use that path. It may be placed for privacy, or to have a guest avoid a dangerous or unpleasant part of the garden. This sculpture was inspired by Nabuo Sekine and the Mono Ho movement. This is a Japanese art movement related to Land Art, which encouraged the production of objects, usually of natural materials. If you grow up in Pittsburgh, cast iron is a natural material.
The proposed sculpture is a granite boulder, wrapped in a one piece, cast-in-place iron cage, topped with an industrial lifting ring. Iron and granite have similar coefficients of expansion with heat, and iron-granite composites were suggested as a construction material a long time ago. A second piece could be cast, if time and materials allow, with a hole drilled through a boulder, capped at one end with a ring, and the other end with a flange or washer, cast as a single piece.