Octahedrite - large cut-polished-nitric acid etched slice of the Canyon Diablo Meteorite that fantastically displays the Widmanstätten structure.

Meteor Crater (Barringer Crater) in the Arizona desert was formed by the impact of an octahedrite ~49,000 years ago during the Late Pleistocene. The rock shown here is a fragment of the impactor, the Canyon Diablo Meteorite. Such fragments have been collected for decades from the desert surrounding the crater. Canyon Diablo is composed of ~90% kamacite, ~1-4% taenite, and up to 8.5% troilite-graphite nodules (FeS & C). The original mass has been estimated to be 100 feet across & about 60,000 tons. Canyon Diablo rocks are well dated to 4.55 billion years.