Tarda Chondrite Meteorite Fragment with Case - 2020 Witnessed Fall!

The Tarda Carbonaceous Chondrite Meteorite

On Tuesday the 25th of August, 2020, around 2:30 pm Moroccan time, a fireball was widely witnessed by people in southern Morocco from Alnif, Zagora, Tazarine, and Rich. The fireball trajectory was from the SW to NE. A search was immediately undertaken by local residents and meteorite hunters between Goulmima and Errachidia. Hundreds of people began searching on the same day, and the first piece was found the following day by Alalou Youssef close to his village of Tarda. The fall location is crossed by the national road linking Ouarzazate to Errachidia, and because of the easy access thousands of people soon traveled to the area.

Several eyewitnesses from areas up to 150 km away were interviewed, and reported a bright yellow, barrel-sized fireball with green edges. The meteor was followed by a thick trail of white smoke that remained suspended for several seconds. The fireball was reported to release little pieces around its edges. Witnesses said the fireball was accompanied by a whistle, followed by multiple detonations. One eyewitness reported an almost vertical trajectory. Thousands of small, mostly complete stones were collected ranging from only a few milligrams to 99 grams, with a total of approximately 4 kg collected. Many pieces were recovered by hunters using magnets. The strewn field is about 3 km long and situated ~10 km east of Tarda.

Meteoritical Bulletin: Entry for Tarda

Carbonaceous chondrites consist of about 5 percent of known chondrites. They contain the highest concentrations of water, organic, and volatile compounds of all chondrites, and, true to their name, contain carbonate minerals! These chondrites are the least oxidized, indicating they came from the outer asteroid belt or beyond. Because of their unique compositions, they are some of the most frequently studied meteorites in the world, and have been considered as an origin for life due to their abundance of organic compounds, including amino acids.

Due to their complexity and variety, carbonaceous chondrites have several sub-classes grouped by chondrule width, each named after the type specimens of each class. CI carbonaceous chondrites, the class of finest grains, are named for the Ivuna meteorite that fell in Tanzania in 1938. CI chondrites almost entirely lack chondrules, and are composed mostly of fine-grained material that underwent aqueous alteration on their parent asteroids. Their chemical composition most closely resembles the sun’s photosphere of any chondrite. Other notable classes include:

CO and CM (Ornans/Mighei), with the smallest chondrules;

CR (Renazzo), CB (Bencubbin) and CH (high metal), which contain unique chondrules that formed from impacts after normal chondrules formed;

CV (Vigarano) and CK (Karoonda), two groups with distinctively large chondrules that formed only once at the beginning of the solar system; and

CL (Loongana), which contain large chondrule and calcium-aluminum-rich inclusions, or CAIs, but low amounts of volatile compounds and matrix.

About Chondrites

Chondrites are stony (non-metallic) meteorites that have not been modified by either melting or differentiation of the parent body. They 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.