Superman Vol 1 #233 January, 1971
Superman breaks loose
Cover artist: Neal Adams Writer: Dennis O'Neil Penciler: Curt Swan Inker: Murphy Anderson
Jor-El's Golden Folly
Writer: E. Nelson Bridwell Penciler: Murphy Anderson Inker: Murphy Anderson
Why is this issue important? First part of the Sandman storyline. Also, an experiment involving kryptonite goes haywire causing all kryptonite on planet earth to turn into harmless iron. This leads the reader to believe Superman is now completely invulnerable! The chain breaking symbolism being a huge factor in the iconic Adams cover art. Page 13