BIG IRON — Canyon Diablo Meteorite

With a Campo Cielo and Henry down the centerline of our conference table. Each of these iron-nickel meteorites has a very different patina.

Meteor Crater formed in a fraction of a second 50,000 years ago as 175 million tons of limestone and bedrock were uplifted, forming the mile-wide crater rim in the formerly flat terrain. The meteorite was only 150 ft. wide but created a 40-megaton blast, destroying 99.999% of the half-million ton mass and creating a spectacular crater. The Canyon Diablo remains were discovered in 1891, and led to mining attempts to find the missing iron mass for the booming railway industry.

In 1953, Clair Cameron Patterson measured ratios of the lead isotopes in samples of the meteorite. The result permitted a refinement of the estimate of the age of the Earth to 4.55 billion years (Wikipedia).

Coarse octahedrite, IAB-MG. Unlike most iron meteorites (which crystallized in the cores of differentiated asteroids), the IAB group probably formed by a tremendously energetic collision at the surface of a chondritic asteroid. This impact triggered local separation of silicate and metal, and slow cooling of buried molten metal beneath the floor of a crater.