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TIROS
Stony
TYPE:
CLASS:
CLAN:
GROUP:
SUBGROUP:
TYPE PET:
SHOCK STG:
WEATHERING:
COUNTRY:
YEAR:
DESCRIPTION:
ACHONDRITE
VESTA
HED
EUCRITE
-
-
S4
W0
BRAZIL - MG
2020
Cumulate Eucrite, Shock Stage S4, Weathering W0.
PETROGRAPHY:
Three thin sections were analyzed, it is a coarse-grained (~1 mm) eucrite with a cumulate texture. It Consists mainly of anorthitic plagioclase feldspar, ortho and clinopyroxene with minor amounts of ferroan olivine, SiO2, troilite, phosphate and ilmenite. At those small sections no chromite neither Fe-metal were observed. The most abundant pyroxene is pigeonite. Some grains exhibit subsolidus augite exsolution. From the plagioclase An content and the texture, it can be classified as a cumulate eucrite. It shows undulatory extinction and planar fractures in plagioclases and planar and irregular fractures and weak mosaicism in some pyroxene grains are indicatives of a shock stage S4.
GEOCHEMISTRY:
Electron microprobe analysis yields: Low-Ca pyroxene: Fs39.8±11.5Wo6.3±1.8, Fe/Mn=34.1±1.5 (n=36). Rich-Ca pyroxene: Fs49.5±6.1Wo24.8±7.9, Fe/Mn=34.7±7.0 (n=60). Olivine: Fa64.7±0.6 (n=9). Plagioclase: An93.4±2.8Ab6.4±2.7Or0.2±0.1 (n=58).
CLASSIFICATION:
Cumulate Eucrite. Weathering (W0) and moderately shocked (S4)
CLASSIFIERS:
M. E. Zucolotto and A. A. Tosi
HISTORY:
On May 8, 2020, at 06:25:15 UTC, a bright fireball was seen from some cities of Minas Gerais and São Paulo states, Brazil. A loud explosion sound was heard in at least 18 cities in the Triângulo Mineiro region. Eight weather cameras from "Clima Ao Vivo" recorded the fireball from seven cities in Minas Gerais, São Paulo and Paraná states. The fireball flash was also detected by GLM instrument on GOES-16 satellite. Analyzing the videos the BRAMON (Brazilian Meteor Network) calculated that the meteor traveled on a southwest-to-northeast trajectory, with velocity of 18.5 km/s, in a 15.8 deg inclination (relative to ground) crossing 180.1 km in 9.76 " and extinguished at 29.7 km high, 9.2 km west of Tiros city, MG. A 84 × 7 km2 strewn field was calculated by Jim Goodall covering a vast area between Tiros and Morada Nova de Minas city. Searches were performed by residents and by meteorite hunters, but with Covid 19 and the vast region covered by mountain and vegetation, no fragment was found. In early September when cutting the vegetation, he found a stone that drew his attention, but let it in the same place. On September 18, Mr. Titota found this shiny black stone just 150 m from the farmhouse and brought it to his wife’s rock collection. He made a video and send to a friendship whatsapp group. The priest José Luis de Araujo Paiva, who participated in the group, suspected to be a meteorite and sent the video to Sandro Barcelos, from Tirense Noticias website, that published the video. The video was shared by @mulheresdeestrelas. Through the @mulheresdeestrelas website and Sandro, The Meteoríticas found the owner of the meteorite. The finder and his family assure that they never saw that rock before. Since the find place is only about 30 km from the calculated strewn field and due to the meteorite be so fresh, it is probably associated with the May fireball.
All information that does not have a specific source was extracted from the Meteoritical Bulletin Database.
All images are copyrighted.
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