.08" Winchcombe Chondrite Meteorite Fragment - 2021 Fall

Hammer stones are the names given to meteorite fragments that hit man-made objects, animals, or people when they fall. Hammer stones are often identified by the scuffed fusion crusts that can contain traces of paint, rubble, or other materials from the objects they hit. Because they are so rare, they are valued collectors' items. Often the items hammer stones hit go up in value, just be being damaged by a meteorite!

Winchcombe is the name given to a carbonaceous chondrite that landed on an English driveway on February 28, 2021. At just about 9:00 PM local time, observatories and meteor observation cameras around the British Isles picked up a bolide making way for the United Kingdom. Numerous witnesses in England recalled a sonic boom over. The next morning, the Wilcock family of Winchcombe, Gloucestershire woke up to their driveway covered in powder and a pile of stones that left a small dent in the tarmac. The Wilcocks reported the impact to the UK Meteor Observation Network, eventually collecting about 600 grams from their property and from neighbors. Later laboratory analysis revealed that the Winchcombe stones are about 4.6 billion years old--as old as the solar system!--and likely originated from the asteroid belt.

Winchcombe is a CM carbonaceous chondrite, typically a dark brecciated stone with black to almost brownish fusion crust on larger fragments. Much of the meteorite is in powder form, and the intact stones are still quite crumbly.

Because it was collected so quickly after its fall, Winchcombe is considered quite a pristine meteorite that offers scientists a wealth of information about asteroids as they exist before falling to Earth as meteors. The roughly meter-wide impact crater was also removed from the Wilcocks' driveway shortly after collection and is now on display at the Natural History Museum in London.

About Chondrites

A chondrite is a stony (non-metallic) meteorite that has not been modified by either melting or differentiation of the parent body. Chondrites are formed when various types of dust and small grains in the early Solar System accreted to form primitive asteroids. Some such bodies are captured in the planet’s gravity well and pulled to the surface. They are by far the most common type of meteorite, representing about 86 percent of all meteorites that have fallen to Earth.

Prominent among the components present in chondrites are the enigmatic chondrules, millimeter-sized spherical objects that originated as freely floating, molten or partially molten droplets in space; most chondrules are rich in the silicate minerals olivine and pyroxene. Chondrites also contain particles of various metals such as nickel, iron, and aluminum. These formed at the very beginning of the solar system and aggregated over time: they are the oldest rocks known on Earth!

Chondrites are divided into about fifteen distinct groups on the basis of their mineralogy, bulk chemical composition, and oxygen isotope compositions. The various chondrite groups likely originated on separate asteroids or groups of related asteroids. Each chondrite group has a distinctive mixture of chondrules, refractory inclusions, matrix (dust), characteristic chondrule sizes, and other components. Other ways of classifying chondrites include weathering and shock. The L chondrite group is the most common of these.