The Allende meteorite is the largest carbonaceous chondrite ever found on Earth. The fireball was witnessed at 01:05 on February 8, 1969, falling over the Mexican state of Chihuahua. After breaking up in the atmosphere, an extensive search for pieces was conducted and it is often described as "the best-studied meteorite in history". The Allende meteorite is notable for possessing abundant, large calcium-aluminium-rich inclusions, which are among the oldest objects formed in the Solar System.
Carbonaceous chondrites comprise about 4 percent of all meteorites
observed to fall from space. Prior to 1969, the carbonaceous chondrite
class was known from a small number of uncommon meteorites such as Orgueil, which fell in France in 1864. Meteorites similar to Allende were known, but many were small and poorly studied.
Fall
The original stone is believed to have been approximately the size of
an automobile traveling towards the Earth at more than 10 miles per
second. The fall occurred in the early morning hours of February 8,
1969. At 01:05 a huge, brilliant fireball
approached from the southwest and lit the sky and ground for hundreds
of miles. It exploded and broke up to produce thousands of fusion
crusted individuals. This is typical of falls of large stones through
the atmosphere and is due to the sudden braking effect of air
resistance. The fall took place in northern Mexico, near the village of
Pueblito de Allende in the state of Chihuahua. Allende stones became one
of the most widely distributed meteorites and provided a large amount
of material to study, far more than all of the previously known
carbonaceous chondrite falls combined.