15. July 2020

Ger­many's largest ev­er stony me­te­orite found in Blaubeuren

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The 30-kilogram ‘Blaubeuren’ meteorite
The 30-kilo­gram ‘Blaubeuren’ me­te­orite
Image 1/8, Credit: Gabriele Heinlein

The 30-kilogram ‘Blaubeuren’ meteorite

It is a sci­en­tif­ic sen­sa­tion. In 1989, while dig­ging a ca­ble trench on his prop­er­ty in Blaubeuren, near Ulm, a res­i­dent came across a stone that seemed un­usu­al­ly heavy and had mag­net­ic prop­er­ties. The an­gu­lar chunk of rock then lay in the gar­den for decades. Af­ter 31 years, the find­er want­ed to know for sure whether it could be a me­te­orite and he re­port­ed his find to the Ger­man Aerospace Cen­ter (DLR) in Jan­uary 2020. On­ly a few days lat­er, it was clear that the find was in­deed a stony me­te­orite with a mass of over 30 kilo­grams, the largest ev­er found in Ger­many. ‘Blaubeuren’, the of­fi­cial name giv­en to the find by the Me­te­orit­i­cal So­ci­ety, prob­a­bly fell to Earth sev­er­al hun­dred years ago, be­cause its ex­te­ri­or shows strong signs of weath­er­ing.
The first clear indication that ‘Blaubeuren’ is a meteorite
The first clear in­di­ca­tion that ‘Blaubeuren’ is a me­te­orite
Image 2/8, Credit: Gabriele Heinlein

The first clear indication that ‘Blaubeuren’ is a meteorite

Af­ter send­ing im­ages, the find­er sent a frag­ment weigh­ing 23.4 grams, cut off from the main ‘Blaubeuren’ mass, to the DLR me­te­orite ex­pert Di­eter Hein­lein. Af­ter a vi­su­al in­spec­tion, the ex­pert recog­nised the pres­ence of iron ore, but then he took a di­a­mond saw and cut the small piece open. Hein­lein then saw a ma­trix of mil­lime­tre-sized chon­drules, spheres that are typ­i­cal for stony me­te­orites. These small chon­drules were cre­at­ed dur­ing the for­ma­tion of the So­lar Sys­tem 4.5 bil­lion years ago and rep­re­sent the ba­sic build­ing blocks of all the plan­ets. He al­so dis­cov­ered char­ac­ter­is­tic met­al in­clu­sions. Thus, it was con­firmed that this frag­ment was in­deed part of a me­te­orite.
Thin sections of ‘Blaubeuren’ under a polarisation microscope
Thin sec­tions of ‘Blaubeuren’ un­der a po­lar­i­sa­tion mi­cro­scope
Image 3/8, Credit: Addi Bischoff, Institute for Planetology, WWU Münster

Thin sections of ‘Blaubeuren’ under a polarisation microscope

The me­te­orite ‘Blaubeuren” comes un­der the clas­si­fi­ca­tion of stony me­te­orites, in the class H4-5 chon­drit­ic brec­cia. When ex­am­in­ing wafer-thin, light-trans­mit­ting rock sam­ples, usu­al­ly 25 mi­crome­tres (thou­sandths of a mil­lime­tre) thick, and us­ing po­larised light, the con­stituent min­er­als can be iden­ti­fied by their char­ac­ter­is­tic colours and out­lines. ‘Blaubeuren’ con­tains nu­mer­ous crys­tallised melt droplets with round­ed out­lines – chon­drules. This im­age shows three grain-shaped olivine chon­drules, more strip-shaped py­rox­ene-bear­ing por­phyrit­ic chon­drules and a ra­di­al py­rox­ene chon­drule (bot­tom right). Olivine and py­rox­ene – alu­mini­um-con­tain­ing sil­i­cates with high pro­por­tions of iron and mag­ne­sium – are typ­i­cal, widespread con­stituent min­er­als in ig­neous rocks. These are po­lar­i­sa­tion mi­cro­scope im­ages pro­duced us­ing crossed po­laris­ers.
The cut – afterwards, the origin of ‘Blaubeuren’ became obvious
The cut – af­ter­wards, the ori­gin of ‘Blaubeuren’ be­came ob­vi­ous
Image 4/8, Credit: Gabriele Heinlein

The cut – afterwards, the origin of ‘Blaubeuren’ became obvious

The main piece of the ‘Blaubeuren’ me­te­orite, which weighs over 30 kilo­grams and is strong­ly weath­ered, was cut fol­low­ing agree­ment with the find­er, to en­able clos­er ex­am­i­na­tion of the chon­drit­ic struc­ture of the me­te­orite and its in­clu­sions. For this pur­pose, ‘Blaubeuren’ was brought to the work­shop of stone­ma­son and sculp­tor Pe­ter Frae­fel at Min­del­heim, in the All­gäu dis­trict. There, af­ter in­ten­sive plan­ning and dis­cus­sions, a 576-gram cor­ner of the me­te­orite was sawn off on 30 May 2020.
Laser guided stone saw – the opening of ‘Blaubeuren’
Laser guid­ed stone saw – the open­ing of ‘Blaubeuren’
Image 5/8, Credit: Gabriele Heinlein

Laser guided stone saw – the opening of ‘Blaubeuren’

The re­moval of the cor­ner sec­tion, which was to be cut off the ‘Blaubeuren’ me­te­orite with a di­a­mond saw, was first sim­u­lat­ed with a tem­plate and then the find was clamped in­to the stone saw­ing de­vice. A laser was then used to con­firm the me­te­orite was in the de­sired po­si­tion in the cut­ting plane be­fore the di­a­mond saw cut through ‘Blaubeuren’ in the plane marked by the laser.
Cut surface of ‘Blaubeuren’ with metallic inclusions
Cut sur­face of ‘Blaubeuren’ with metal­lic in­clu­sions
Image 6/8, Credit: DLR/U. Köhler

Cut surface of ‘Blaubeuren’ with metallic inclusions

The cut­ting open of ‘Blaubeuren’ brought the ob­vi­ous proof that the 1989 find from a gar­den in Swabia is in fact a me­te­orite. In ad­di­tion to the typ­i­cal ma­trix of mil­lime­tre-sized chon­drules (which can be seen in this mag­ni­fied pho­to and al­so in the mi­cro­scope im­age), the bright­ly re­flect­ing cut sur­faces of metal­lic in­clu­sions are al­so char­ac­ter­is­tic of a stony me­te­orite. ‘Blaubeuren’ con­tains around five to 10 per­cent iron and nick­el. The cut sur­face has a width of ap­prox­i­mate­ly 13 cen­time­tres.
Meteorite size comparison – ‘Blaubeuren’ with ‘Machtenstein’ and ‘Cloppenburg’
Me­te­orite size com­par­i­son – ‘Blaubeuren’ with ‘Macht­en­stein’ and ‘Clop­pen­burg’
Image 7/8, Credit: DLR/U. Köhler

Meteorite size comparison – ‘Blaubeuren’ with ‘Machtenstein’ and ‘Cloppenburg’

‘Blaubeuren’ is the largest and heav­i­est stony me­te­orite ev­er found in Ger­many. Its ex­te­ri­or di­men­sions are ap­prox­i­mate­ly 28 by 25 by 20 cen­time­tres. In this im­age, for com­par­i­son, is a cast mod­el of the me­te­orite ‘Macht­en­stein’ (right), which, sim­i­lar to ‘Blaubeuren’, was on­ly recog­nised as a me­te­orite in 2014, decades af­ter its dis­cov­ery in the 1950s. It is named af­ter the place where it was found, Macht­en­stein, which is near Schwab­hausen in Up­per Bavaria; it orig­i­nal­ly weighed 1422 grams. In the fore­ground, the 142-gram ‘Clop­pen­burg’ me­te­orite, which was found in March 2017 near the city of the same name in Low­er Sax­ony.
Observed meteorite falls and chance meteorite finds in Germany
Ob­served me­te­orite falls and chance me­te­orite finds in Ger­many
Image 8/8, Credit: DLR-European Fireball Network/Dieter Heinlein

Observed meteorite falls and chance meteorite finds in Germany

The map on the left shows the lo­ca­tion, of­fi­cial name, and year of dis­cov­ery of 19 me­te­orites which were found by chance and recog­nised as me­te­orites, but whose fall was not ob­served. Among them is the ‘Blaubeuren’ me­te­orite, which fell to Earth long be­fore its dis­cov­ery in 1989, pos­si­bly some cen­turies ago. It land­ed in the val­ley of the riv­er Blau near Blaubeuren, a pic­turesque me­dieval town 14 kilo­me­tres west of Ulm. The map on the right shows the name and year of fall of 33 me­te­orites in Ger­many the fall of which was di­rect­ly ob­served. The ‘Blaubeuren’ me­te­orite is not in­clud­ed, but the map does in­clude, among oth­ers, the me­te­orite ‘Neuschwanstein’, the fall of which was de­tect­ed in 2002 by DLR’s me­te­o­ro­log­i­cal ob­ser­va­tion net­work and whose fall area could be re­con­struct­ed ge­o­met­ri­cal­ly. Af­ter the fall, three frag­ments of ‘Neuschwanstein’ were found.
  • A chondrite weighing 30 kilograms was discovered by chance.
  • A homeowner found the visitor from space in 1989 while digging a cable trench.
  • The meteorite is thought to have fallen to Earth hundreds of years ago.
  • Focus: Planetary research, meteorites, Solar System exploration

Even in science, chance sometimes produces more thrilling discoveries that the most ambitious plans. In 1989, a homeowner was digging a cable trench on his property in Blaubeuren, in the German region of Swabia, when his spade hit a rock measuring 28 by 25 by 20 centimetres. Upon lifting it half a metre to the surface, he found that it was remarkably heavy. He held a magnet to the rock and confirmed that it contained iron. The angular boulder was then left lying in the garden for decades. Only 31 years later did it occur to the finder that it might be a visitor from space. In January 2020, he reported his find to the Institute of Planetary Research at the German Aerospace Centre (Deutsches Zentrum für Luft- und Raumfahrt; DLR). Then, after the first scientific analyses, came the sensational discovery that the object is indeed a stony meteorite. In addition, with a mass of over 30 kilograms, it is the largest ever found in Germany. On 7 July 2020, the Meteoritical Society, the international organisation of meteorite researchers, which documents all meteorite finds and falls worldwide, confirmed in its bulletin that this find had been recognised as a meteorite. It has been officially named 'Blaubeuren' after the place where it was discovered, the small medieval town of Blaubeuren, 17 kilometres west of Ulm.

"This is a standard type H4-5 chondrite," says Dieter Heinlein, a meteorite expert at the DLR Institute of Planetary Research in Augsburg and coordinator of DLR's research into and studies of 'Blaubeuren'. "The find has a mass of 30.26 kilograms, making it the largest stony meteorite ever to be found in Germany." Prior to 'Blaubeuren', the 'Benthullen' meteorite, which was discovered near Oldenburg, was the record-holder, with a mass of 17.25 kilograms. The density of 'Blaubeuren' has been determined to be 3.34 grams per cubic centimetre; this is particularly high due to the meteorite’s significant iron and nickel content.

A sensational find at the end of a series of coincidences

The history of 'Blaubeuren' is quite extraordinary. At first the rock, which was a mere obstacle to the digging of the cable trench and had to be cleared out of the way, was simply overlooked. Even an expert would hardly have guessed that the heavily weathered boulder was actually a meteorite. After all, potential meteorites generally feature a characteristic dark fusion crust, caused by heating during their high-speed descent through Earth's atmosphere.

The meteorite languished in the landowner's garden until 2015 and became increasingly weathered over time. At that point, he almost got rid of it altogether, saying: "The boulder was actually on the trailer, ready to be taken away." Fortunately, he had second thoughts and transferred the rock to his cellar, where it was kept safe and dry in a cupboard. In January 2020, he decided to find out about the composition and background of this strange rock once and for all, and contacted DLR. Heike Rauer, Director of the DLR Institute of Planetary Research, and Jürgen Oberst, who oversees the European Fireball Network at DLR, put the finder in contact with Dieter Heinlein, DLR's meteorite expert in Augsburg. The Institute maintains a website with information and a checklist for identifying potential meteorites, plus an address for reporting meteorite sightings.

The cut fragment that revealed the secret of 'Blaubeuren'

After a discussion on the phone and the sending of numerous images, the finder sent a fragment weighing 23.4 grams to Heinlein. From a visual inspection, the expert could immediately recognise the presence of iron ore, but when he reached for his diamond saw and cut the small piece open, he was utterly amazed. Heinlein saw a matrix of millimetre-sized chondrules that is typical of stony meteorites. These small spheres were created during the formation of the Solar System 4.5 billion years ago and represent the original building blocks of all the planets. He also discovered the characteristic metal inclusions of a meteorite. "I was immediately pretty certain that this was a fragment from a meteorite," says the DLR expert.

On 9 February 2020, the finder entrusted the main part of the meteorite to DLR for further investigations, including a precise determination of the density of the material. A while later, another fragment weighing 410 grams was found in the same garden. This additional find was also subjected to intensive scientific investigation. In consultation with the finder, the main body, which weighed over 30 kilograms and was heavily weathered on the outside, was cut into in order to examine the chondritic structure of the meteorite and its inclusions in greater detail. Even Heinlein, who has a large collection of specialist tools, was somewhat overwhelmed: "Of course, I had never had such a large piece of rock in my laboratory." He found a specialist company to help – the workshop of the stonemason and sculptor Peter Fraefel in Mindelheim, Allgäu. On 30 May 2020, after intensive planning and preliminary discussions, a 576-gram corner of the meteorite was removed using a diamond saw.

Saw­ing in the stone­ma­son’s work­shop
Af­ter in­ten­sive plan­ning and dis­cus­sions, stone­ma­son and sculp­tor Pe­ter Frae­fel sawed off a cor­ner of the me­te­orite weigh­ing 576 grams.
Credit: DLR/Gabriele Heinlein

A journey through three laboratories – 'Blaubeuren' analysed

Chemical and mineralogical analyses were then carried out in three different, specialist laboratories – albeit very discreetly, as Heinlein and DLR suspected that the find might cause quite some excitement. At the Museum of Natural History in Bern, Beda Hofmann used an X-ray fluorescence spectrometer to determine the meteorite’s concentrations of barium and strontium isotopes. The results revealed that the rock had become weathered after falling onto the Swabian Jura. This confirmed that 'Blaubeuren' is definitely Swabian.

In a laboratory at Radiation Protection, Analytics & Disposal (Strahlenschutz, Analytik & Entsorgung Rossendorf e. V.; VKTA), Detlev Degering conducted measurements of the radioisotope content in the main meteorite mass and the subsequent find, and also analysed soil samples from the garden where they were discovered. This enabled the proportions of the cosmogenic, terrestrial and anthropogenic (i.e. human-caused) radioisotope components to be determined. The aim is to find out roughly when the meteorite fell to Earth. Judging by its weathering, this could have happened several centuries ago. Investigations in this area are still ongoing.

'Blaubeuren' is the result of a cosmic collision

Lastly, thin sections were prepared by the Institute of Planetology at the University of Münster (Westfälischen Wilhelms-Universität Münster; WWU) in order to determine the chemical, mineralogical and petrological composition of the object. "'Blaubeuren' is obviously a breccia, in other words a rock that has been created by the agglomeration of a number of fragments," explains Addi Bischoff from WMU. “In the past, the Blaubeuren meteorite experienced at least one violent collision. We often see this with H4 and H5 chondrites." Under the surface lies the iron and magnesium silicate olivine, which makes up almost three quarters of the mineralogical constituents of the meteorite. Following these investigations, 'Blaubeuren' was submitted to the Meteoritical Society's Nomenclature Committee by Kerstin Klemm of WWU on 16 June 2020. It was recognised as a meteorite just three weeks later.

Meteorites play a hugely important role in the study of the early development of the Solar System. They arrive on Earth of their own volition and 'free of charge'. Most of them originate in the asteroid belt between Mars and Jupiter before their orbit is disrupted, putting them on a collision course with Earth. They enter the atmosphere at high speed so, even if they were originally large masses of rock or iron, often only a small remnant actually hits Earth as a meteorite. For now, Blaubeuren will remain with its finder, but ultimately the owner wishes Germany's largest stony meteorite to be on permanent display in a museum, so that the public will also be able to marvel at this 'Swabian that fell from the sky'.

Contact
  • Falk Dambowsky
    Ed­i­tor
    Ger­man Aerospace Cen­ter (DLR)
    Me­dia Re­la­tions
    Telephone: +49 2203 601-3959
    Fax: +49 2203 601-3249
    Linder Höhe
    51147 Cologne
    Contact
  • Prof. Jürgen Oberst
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Plan­e­tary Re­search, Plan­e­tary Geodesy
    Telephone: +49 30 67055-336
    Fax: +49 30 67055-402

  • Dieter Heinlein
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Plan­e­tary Re­search
    Telephone: +49 176 47691073
    Rutherfordstraße 2
    12489 Berlin
    Contact
  • Ulrich Köhler
    Pub­lic re­la­tions co­or­di­na­tor
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Plan­e­tary Re­search
    Telephone: +49 30 67055-215
    Fax: +49 30 67055-402
    Rutherfordstraße 2
    12489 Berlin
    Contact

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