observed fall in Morocco
What is Tirhert?
An extraterrestrial gabbro (coarse-grained basalt), the Tirhert meteorite from the asteroid 4 Vesta fell on July 9, 2014 in southern Morocco. It produced an intense fireball in the sky as it fell and left behind fragments on the ground. Approximately 8 kg have been found. The picture above shows a thin slice with the silvery black fusion crust on the left and the unaltered minerals on the right.
What is 4 Vesta? Vesta was the 4th asteroid discovered (in 1807), following Pallas, Ceres, and Juno just years before. It is the second largest body in the asteroid belt after Ceres.
About 1 in 16 of all meteorites that land on earth are from Vesta. These stony meteorites from Vesta are grouped as HED meteorites: howardites, eucrites and diogenites. Tirhert is a cumulate eucrite indicating it cooled slower in the shallow crust compared to the surface basalts.
How do we know Tirhert is from Vesta? A combination of spectral data, geochemical analyses and a year-long visit from NASA’s Dawn spacecraft in 2011-2012, has identified the billion-year-old giant Rheasilvia Crater near the south pole as the likely source. Yes, we’ll be writing more about this very soon!
Under the Microscope
Tirhert under transmitted, cross-polarized light has a little of everything. Very fine to large mineral grains, white plagioclase to bright pink, green and blue pyroxenes. The randomness of the texture and color within the design makes this abstract piece truly sci-art.
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