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Narashino
Basic information Name: Narashino
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: Yes, confirmed fall
Year fell: 2020
Country: Japan
Mass:help 350 g
Classification
  history:
Recommended:  H5    [explanation]

This is 1 of 10132 approved meteorites (plus 18 unapproved names) classified as H5.   [show all]
Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 1 Nov 2020
Writeuphelp
Writeup from MB 109:

Narashino        35°41’26"N, 140°01’51"E

Kanto, Japan

Confirmed fall: 2020 Jul 2

Classification: Ordinary chondrite (H5)

History: At 2:32 am JST on July 2, 2020, a bright fireball was observed over the Kanto region, Japan (see IAU CBET No. 4810 for trajectory and orbital information). At the same time, a detonating sound was heard at an apartment in Narashino city, Chiba prefecture, Japan and in the morning at that day, a 63 g fragment was found in the corridor at the second floor of the apartment (35°41’26"N, 140°01’51"E). On July 4, another 70 g fragment was found in the garden of the apartment (35°42’01"N, 140°02’34"E). Both fragments fit together, thus they were originally one mass (No. 1) and were fragmented on impact. The meteorite was reported to the local museum and then brought to NMNS on July 5, where cosmogenic 52Mn, 48V, 54Mn, 22Na and 26Al gamma rays were detected by the pure Ge detector. Several small fragments, 22 g in total were found on a terrace at the fifth floor of the apartment on July 18, thus the total weight of the mass No. 1 is more than 156 g. On July 22, another mass (No. 2) was found in Funabashi city, Chiba about 1 km northeast of the No. 1 site. A roofing tile of an apartment was broken and 2 large fragments, 95 g and 73 g, and 8 small fragments of the meteorite, 184 g in total were found on the ground with roofing tile fragments. Later, 3 small fragments, 10 g in total, were reported, thus the total weight of the mass No. 2 is more than 194 g.

Physical characteristics: Two large fragments of mass No. 1 make a rounded cube shape, half covered by the fusion crust. The first fragment is fresh but second one is slightly rusted due to the rainy weather where it was in the garden for 2 days. Two large fragments of mass No. 2 make a heart-shaped, relatively flat mass half covered by fusion crust. The surface without fusion crust of No. 2 is heavily rusted due to the weather outside for 20 days. The cut surface has no apparent rust, however.

Petrography: Polished thick and thin sections were made from the 70 g fragment of No. 1 and the 73 g fragment of No. 2 at NIPR. Olivine compositions of No. 1 and No. 2 are Fa17.0-18.1 (mean=Fa17.7, N=27) and Fa16.9-18.0 (mean Fa17.6, N=25), and low-Ca pyroxene compositions are Fs15.4-16.5 (mean=Fs15.8, N=13) and Fs15.5-16.2 (mean=Fs15.8, N=19), respectively. No presence of plagioclase >50um indicates that the petrologic type is 5.

Geochemistry: Using small fragments from the 63 g No. 1 fragment and the 73 g No. 2 fragment, rare gas analyses were made at KyuU. The K-Ar gas retension age is about 4.5 Ga (assuming the K content of 780 ppm).

Classification: H5

Specimens: NMNS: 63g for Type specimen; NIPR: 2 polished thick and thin sections

Data from:
  MB109
  Table 0
  Line 0:
State/Prov/County:Kanto
Date:2020 Jul 2
Latitude:35°41'26"N
Longitude:140°01'51"E
Mass (g):350
Pieces:2
Class:H5
Shock stage:S1
Fayalite (mol%):17.7 (16.9-18.1, N=52)
Ferrosilite (mol%):15.8 (15.4-16.2, N=32)
Wollastonite (mol%):1.5. (1.1-2.0, N=32)
Classifier:A. Yamaguchi, NIPR; A. Takenouchi, NIPR; R. Okazaki, KyuU; S. Yoneda, NMNS
Type spec mass (g):63
Type spec location:NMNS
Main mass:Finders
Comments:Submitted by S. Yoneda, NMNS
Institutions
   and collections
NIPR: Antarctic Meteorite Research Center, National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan; Website (institutional address; updated 9 Dec 2013)
NMNS: National Museum of Nature and Science, 4-1-1 Amakubo, Tsukuba, Ibaraki 305-0005, JAPAN, Japan; Website (institutional address; updated 16 Jun 2014)
KyuU: Department of Earth and Planetary Science, Kyushu University Hakozaki, Higashi-ku, Fukuoka-shi 812- 8581, Japan (institutional address)
Chiba: Chiba Institute of Technology, Tsudanuma, Narashino, Chiba 275-0016, Japan (institutional address)
Catalogs:
References: Published in Meteoritical Bulletin, no. 109, in preparation (2020)
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Photos:
CreditPhotos
Public domain photographs:
s-yoneda@kahaku.go.jp      
Geography:

Japan
Coordinates:
     Recommended::   (35° 41' 26"N, 140° 1' 51"E)

Statistics:
     This is 1 of 8 approved meteorites from Kanto, Japan (plus 4 unapproved names)
     This is 1 of 57 approved meteorites from Japan (plus 12 unapproved names)
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