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Basic information Name: Hamburg
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: Yes, confirmed fall
Year fell: 2018
Country: United States
Mass:help 1000 g
Meteoritical Bulletin:  MB 107  (2018)  H4
Recommended:  H4    [explanation]

This is 1 of 6540 approved meteorites (plus 3 unapproved names) classified as H4.   [show all]
Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 2 Mar 2018
Writeup from MB 107:

Hamburg        42°26.82’N, 83°50.5’W

Michigan, United States

Confirmed fall: 2018 Jan 16

Classification: Ordinary chondrite (H4)

History: On 16 January 2018 around 20:10 EST, a fireball was observed and reported by hundreds of people from seven states. The fireball was recorded by multiple security cameras and registered as a 2.0 magnitude earthquake. Mike Hankey (AmMS) calculated the trajectory within one hour. A strewnfield map was produced by Marc Fries (JSC) using weather radar data from radar reflections of falling meteorites. The first fragment was found on 18 January 2018 at 7:50 EST by Robert Ward on Strawberry Lake near Hamburg, Michigan. Five other masses, ranging from 17 to 102.6 g, were found later the same day by Ward, Larry Atkins, and Darryl Landry on Strawberry and Bass Lakes. Thirteen additional pieces were found within two weeks of the fall.

Physical characteristics: Most stones are fully covered by fusion crust.

Petrography: Metal-rich texture typical of H chondrites is apparent on cut surfaces. The metal volume estimate is 9% based on an Fe EDS map. Chondrules are visible in polished section. The average chondrule diameter is 0.4±0.2 mm (N=26). Several chondrules are well-defined and have sharp boundaries. Pyroxenes are mostly orthopyroxene and less abundant clinopyroxene as determined with Raman spectroscopy. Feldspar grains vary in size and measure 3.4±2.2 μm (n=64) in a representative field of view. Chromites are impact fractured. No chromite veinlets nor opaque veins are observed within the meteorite. Phosphates account for about 0.5% of the meteorite and occur mainly as merrillite (0.4%) and apatite (0.1%). In a representative field of view, grain sizes for merrillite average around 100 µm and range from <1 µm up to 430 µm (n=37); apatite ranges from 70 µm to 310 µm with an average of 150 µm (n=8). The meteorite appears very weakly shocked. Melt veins (Fe-sulfide) occur only in close proximity to the fusion crust.

Geochemistry: Mineral Compositions and geochemistry: Olivine Fa18.7±0.7 (N=34). The average composition of Ca-poor px is Fs16.3±0.4Wo1.3±0.1 (n=80). Feldspar is present with an average composition of An14.0±4.0Ab81.1±3.0 Or4.8±1.3 (n=13). Chromite: TiO2=2.0±0.4 wt% V2O3=0.8±0.2 wt% (N=25). Apatite contains about 5 wt% Cl and <1 wt% F.

Classification: The petrology, mineral chemistry and compositional hetereogeneity of the minerals listed is consistent with H4 chondrites. The meteorite is classified as H4, S2, W0.

Specimens: Type specimen 22.8 g and polished section at FMNH; 102.6 g specimen with Robert Ward; 44.5 g specimen with Terry Boudreaux.

Data from:
  Table 0
  Line 0:
Date:2018 Jan 16
Mass (g):~1000
Shock stage:S2
Weathering grade:W0
Fayalite (mol%):18.7±0.7 (1SD; N=34)
Ferrosilite (mol%):16.3±0.4 (1SD; N=80)
Wollastonite (mol%):1.3±0.1 (1SD; N=80)
Classifier:P. Heck, Jennika Greer, FMNH
Type spec mass (g):22.7
Type spec location:FMNH
Main mass:RWard
Comments:P.R. Heck acknowledges Robert Ward for donating his first meteorite to FMNH, Terry Boudreaux for support, the Tawani Foundation for funding, Jim Holstein and Drew Carhart for help with sample preparation.; submitted by Philipp R. Heck, Jennika Greer
   and collections
FMNH: NW Quadrant/Geology The Field Museum of Natural History 1400 South Lake Shore Drive Chicago, IL 60605-2496, USA, United States; Website (institutional address; updated 22 May 2024)
JSC: Mailcode XI, 2101 NASA Parkway, NASA Johnson Space Center, Houston, TX 77058, United States; Website (institutional address; updated 28 Jul 2022)
Boudreaux: Terry Boudreaux, Illinois, United States (private address)
RWard: No contact information provided. (private address)
AmMS: American Meteor Society 54 Westview Crescent, Geneseo NY 14454, United States; Website (institutional address; updated 7 Mar 2018)
References: Published in Meteoritical Bulletin, no. 107, MAPS 55, 460-462
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United States
     Recommended::   (42° 26' 49"N, 83° 50' 30"W)

     This is 1 of 12 approved meteorites from Michigan, United States (plus 1 impact crater)
     This is 1 of 1930 approved meteorites from United States (plus 866 unapproved names) (plus 28 impact craters)
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