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Basic information Name: Berthoud
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: Yes
Year fell: 2004
Country: United States
Mass:help 960 g
Meteoritical Bulletin:  MB 94  (2008)  Eucrite-mmict
Recommended:  Eucrite-mmict    [explanation]

This is 1 of 177 approved meteorites classified as Eucrite-mmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Approved 27 Jun 2008
Revised 17 Feb 2012: Added info on specimens
Writeup from MB 94:

Berthoud                    40°1821.0’’N, 105°123.7’’W

Weld County, Colorado, USA.

Fall: 5 October 2004, ~13:30 local daylight time (UT-6)

Achondrite (eucrite)

History: A meteorite fell ~4 km east of Berthoud, Colorado. According to information from those who visited the site, Megan and Andy Clifford “had just walked out of their house when they were distracted by whistling noise and a thump. Megan observed some dust kicked up in a horse pen about 100 feet away. After a short search, they recovered the object.” (http://www.cloudbait.com/science/bermet.html). The meteorite embedded itself a few inches below the surface.

Physical characteristics: A single stone, 120 mm across, ~960 g was recovered soon after the fall. Fresh, glossy, black fusion crust covered the stone except for a small broken corner. The interior is medium gray in color.

Petrography: (D. H. Hill, UAz) Overall, texture is ophitic to subophitic with evidence of brecciation and recrystallization. The meteorite is shocked with occurrences of dislocated grains; fine melt veins run through the sample. Exsolution is observed in pyroxenes; several exhibit finely spaced fractures. Plagioclase contains many blebby inclusions. Accessory minerals include chromite, phosphates, iron sulfides, ilmenite, and silica.

Mineral compositions and geochemistry: (M. Killgore, UAz) Opx (Fs54.03En42.82Wo3.15); Cpx (Fs31.21En35.80Wo33.00); Plag (An82.72Ab16.04Or1.24); pyroxene molar Fe/Mn = 31. Oxygen isotopes (R. Greenwood, I. Franchi, OU) δ17O = 1.58‰; δ18O = 3.46‰; Δ17O = -0.227‰.

Classification: Achondrite (eucrite)

Type specimens: A total sample mass of 24.3 g and one thin section are on deposit at UA; owners hold the main mass; several thin sections with anonymous persons.

Writeup from MB 100:

Berthoud, updated information.

Several large pieces of Berthoud are now held by UNM, including a 247 g crusted end piece and a 202 g full slice.
Data from:
  Table 3
  Line 2:
State/Prov/County:Weld County, Colorado
Mass (g):960
Class:Eucrite (monomict breccia)
Ferrosilite (mol%):54.03
Wollastonite (mol%):3.15
Classifier:D. H. Hill, UAz
Type spec mass (g):24.3
Type spec location:UAz
Main mass:anonymous
Plots: O isotopes:  
   and collections
OU: Planetary and Space Sciences Department of Physical Sciences The Open University Walton Hall Milton Keynes MK7 6AA United Kingdom, United Kingdom (institutional address; updated 8 Dec 2011)
UAz: Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721, United States (institutional address; updated 14 Jan 2012)
UNM: Institute of Meteoritics MSC03 2050 University of New Mexico Albuquerque NM 87131-1126 USA, United States; Website (institutional address; updated 12 Feb 2015)
Killgore: Marvin and Kitty Killgore, Southwest Meteorite Laboratory, P.O. Box 95, Payson, AZ 85547, United States; Website (private address)
References: Published in Meteoritical Bulletin, no. 94, MAPS 43, 1551-1588 (2008)
Published in Meteoritical Bulletin, no. 100, MAPS 49, E1-E101 (2014)
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Photos from the Encyclopedia of Meteorites:
Chris L. Peterson      
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Gerald Armstrong   
Michael S. Scherman   
Woreczko Jan & Wadi   

United States
     Recommended::   (40° 18' 21"N, 105° 1' 24"W)

     This is 1 of 88 approved meteorites from Colorado, United States (plus 5 unapproved names)
     This is 1 of 1783 approved meteorites from United States (plus 352 unapproved names) (plus 28 impact craters)
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