He also conducted a wide range of research at the crater, discovering impactite, iron-nickel spherules related to the impact and vaporization of the asteroid, and the presence of many features still unique to the crater, such as half-melted slugs of meteoric iron mixed with melted target rock. Nininger's discoveries were compiled and published in a seminal work, Arizona's Meteorite Crater (1956).
He explored the crater deeply, finding impactite, iron-nickel spherules connected to asteroid impacts and vaporization, and numerous distinctive features such as half-melted slugs of meteoric iron mixed with melted target rock. Nininger's discoveries were documented in a significant work, Arizona's Meteorite Crater (1956).