header
  MetSoc Home            Publications            Contacts  
Search the Meteoritical Bulletin Database
Last update: 30 Nov 2019
Search for: Search type: Search limits: Display: Publication:
Names
Text help
Places
Classes
Years
Contains
Starts with
Exact
Sounds like
NonAntarctic
Falls  Non-NWAs
What's new
  in the last:
Limit to approved meteorite names
Search text:  
Benenitra
Basic information Name: Benenitra
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: Yes, confirmed fall
Year fell: 2018
Country: Madagascar
Mass:help 20 kg
Classification
  history:
Recommended:  L6    [explanation]

This is 1 of 11000 approved meteorites (plus 6 unapproved names) classified as L6.   [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 11 Apr 2019
Writeuphelp
Writeup from MB 108:

Benenitra        23°26.786’S, 45°4.692’E

Toliara, Madagascar

Confirmed fall: 27 July 2018

Classification: Ordinary chondrite (L6)

History: Reports of a meteor that detonated in a loud explosion, and stones falling from the sky into the town of Benenitra (pop. ~30,000) on the evening of July 27, 2018, were received by a visiting geologist, Timothy Marais, on July 30, 2018. He was shown photographs and several small fragments, two of which he purchased, weighing 99 and 14 g. Roger Gibson and Lewis Ashwal in the School of Geosciences at the University of the Witwatersrand confirmed a meteorite origin for these specimens using petrographic analysis and EMPA. Confirmation of the date and time of the fall was obtained independently when an upper atmosphere infrasound event was identified on a bearing south-southwest of the CTBTO station IS33 near Antananarivo, Madagascar, at 17h16 GMT on July 27 by Dr. Andry Ramanantsoa (Laboratory of Seismology and Infrasound, University of Antananrivo). A weak ground tremor at approximately 17h17 GMT was identified in the data from the seismograph at the Sakaraha (SKRH) station approximately 80 km northwest of Benenitra by Dr Ranto Raveloson (Wits), and was interpreted to be related to the airburst. Magnetic susceptibility measurements were performed by Prof. Susan Webb (Wits).

Physical characteristics: Two broken fragments containing small remnants of bluish-black to brown-black fusion crust and weighing 14 g and 82 g (after thin sectioning) consist of a light-gray matrix with disseminated metal (<1 mm) and some visible chondrules (<5 mm). The edge of the larger fragment, which contains a thin (<0.5 mm), dark-gray melt vein, was sectioned. Photographs taken by local residents show more than a dozen other fragments ranging in mass from ~100-1000 g; these show mostly intact fusion crusts with only limited chipping of edges. Samples range from subangular to subrounded to disc-shaped, with both sharp and rounded edges. Fusion crusts on these samples are generally smooth, with a few shallow regmaglypts.

Petrography: (L.D. Ashwal and R.L. Gibson, Wits) Modal abundances: 50% olivine, 25% low-Ca pyroxene, 5% high-Ca pyroxene, 10% feldspar, 7% troilite, 2% kamacite, 1% taenite, and trace amounts of chromite and a silica-rich phase. Recognizable chondrules range in size between 1 and 4.5 mm in diameter, and include porphyritic olivine and/or pyroxene, barred olivine, radial pyroxene and cryptocrystalline types, although their original textures have been variably modified by secondary thermal effects. Feldspar is almost entirely crystalline, and occurs as irregular grains up to 100 μm across, many of which display twinning. Pyroxenes are untwinned, and most grains exhibit straight extinction, although minor undulatory extinction is present in some grains. Low-Ca pyroxene shows parallel extinction with respect to cleavage traces. High-Ca pyroxene occurs as irregular grains up to 20 μm across; exsolution lamellae were observed in a few grains. Shock features include planar and irregular fractures in olivine, undulatory extinction in feldspar and pyroxenes, and anastomosing opaque shock veins up to 75 μm thick.

Geochemistry: Mineral compositions: (L.D. Ashwal and A. Ziegler) Olivine (Fa24.0±0.8), low-Ca pyroxene (Fs20.4±0.9Wo1.4±0.4), high-Ca pyroxene (Fs8.0± 0.8Wo42.4±1.0), feldspar (Ab79.1±3.1An13.3±1.9Or7.6±1.5), troilite (Fe = 63.3±0.2, S = 36.5±0.3), kamacite (Ni = 5.7±0.7; Co = 0.85±0.05), taenite (Ni = 27.8±1.0).

Classification: Ordinary chondrite (L6), Shock level S3, Weathering level W0.

Specimens: 82 g (R.L. Gibson, Wits), 25.8 g at TCU (donated by Rob Wesel), reports of one or more pieces with masses of up to 15 kg are unconfirmed.

Data from:
  MB108
  Table 0
  Line 0:
State/Prov/County:Toliara
Origin or pseudonym:Benenitra town and surroundings
Place of purchase:Benenitra
Date:27 July 2018
Latitude:23°26.786'S
Longitude:45°4.692'E
Mass (g):20000
Pieces:>10
Class:L6
Shock stage:S3
Weathering grade:W0
Fayalite (mol%):24.0±0.8 (N=26)
Ferrosilite (mol%):20.4±0.9 (N=51); 8.0±0.8 (N=11)
Wollastonite (mol%):1.4±0.4; 42.4±1.0
Magnetic suscept.:4.59
Classifier:L.D. Ashwal and R.L. Gibson, Wits
Type spec mass (g):82, 25.8
Type spec location:Wits, TCU
Main mass:unknown
Finder:Unknown resident(s) of Benenitra, Madagascar.
Comments:Submitted by L.D. Ashwal and R.L. Gibson
Institutions
   and collections
TCU: Oscar E. Monnig Collection, Department of Geology, Texas Christian University, Ft. Worth, TX 76129, United States; Website (institutional address; updated 24 Feb 2012)
Wits: Curator of Fossil and Rock Collections c/o Evolutionary Studies Institute University of the Witwatersrand Private Bag 3 WITS 2050 Johannesburg South Africa, South Africa (institutional address; updated 3 May 2019)
Catalogs:
References: Published in Meteoritical Bulletin, no. 108, in preparation (2019)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Photos uploaded by members of the Encyclopedia of Meteorites.
    (Caution, these are of unknown reliability)
DCOM   
Wang Ziyao            
Woreczko Jan & Wadi   
Public domain photographs:
Lewis D. Ashwal         
Geography:

Madagascar
Coordinates:
     Recommended::   (23° 26' 47"S, 45° 4' 42"E)

Statistics:
     This is the only approved meteorite from Toliara, Madagascar
     This is 1 of 2 approved meteorites from Madagascar
Proximity search:
Find nearby meteorites: enter search radius (km):

Direct link to this page