[meteorite-list] Hamburg Michigan Meteorite Fall is now Official

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Fri, 2 Mar 2018 12:58:18 -0500
Message-ID: <CAKBPJW9omDd=aRQr52qD73ahOYZDSt6ys+D61Jt6znVfJUWrfg_at_mail.gmail.com>

The first meteorite fall of 2018 is now official - Hamburg Michigan. I
have updated the Catalog of Witnessed Falls page to reflect this new
data : http://galactic-stone.com/pages/falls
The first meteorite fall of 2018 is now official - Hamburg Michigan. I
have updated the Catalog of Witnessed Falls page to reflect this new
data : http://galactic-stone.com/pages/falls

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 (AMS) 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. The same day Ward
found two more fragments (102.6 and 44.5 g) on Bass Lake near Hamburg,
and sixteen more pieces were subsequently reported 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 ?m (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 ?m and range from <1 ?m up to 430 ?m
(n=37); apatite ranges from 70 ?m to 310 ?m with an average of 150 ?m
(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.

Meteoritical Bulletin link :
https://www.lpi.usra.edu/meteor/metbull.php?code=66772


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 (AMS) 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. The same day Ward
found two more fragments (102.6 and 44.5 g) on Bass Lake near Hamburg,
and sixteen more pieces were subsequently reported 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 ?m (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 ?m and range from <1 ?m up to 430 ?m
(n=37); apatite ranges from 70 ?m to 310 ?m with an average of 150 ?m
(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 The first meteorite fall of
2018 is now official - Hamburg Michigan. I have updated the Catalog of
Witnessed Falls page to reflect this new data :
http://galactic-stone.com/pages/falls

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 (AMS) 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. The same day Ward
found two more fragments (102.6 and 44.5 g) on Bass Lake near Hamburg,
and sixteen more pieces were subsequently reported 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 ?m (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 ?m and range from <1 ?m up to 430 ?m
(n=37); apatite ranges from 70 ?m to 310 ?m with an average of 150 ?m
(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.

Meteoritical Bulletin link :
https://www.lpi.usra.edu/meteor/metbull.php?code=66772

with Terry Boudreaux.

Meteoritical Bulletin link :
https://www.lpi.usra.edu/meteor/metbull.php?code=66772

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Received on Fri 02 Mar 2018 12:58:18 PM PST