# The anomalous polymict ordinary chondrite breccia of Elmshorn (H3-6)-Late reaccretion after collision between two ordinary chondrite parent bodies, complete disruption, and mixing possibly about 2.8 Gyr ago

Addi Bischoff, Markus Patzek, Romain Alosius, Jean-Alix Barrat, Jasper Berndt, Henner Busemann, Detlev Degering, Tommaso Di Rocco, Mattias Ek, Jérôme Gattacceca, et al.

► To cite this version:

Addi Bischoff, Markus Patzek, Romain Alosius, Jean-Alix Barrat, Jasper Berndt, et al. The anomalous polymict ordinary chondrite breccia of Elmshorn (H3-6)-Late reaccretion after collision between two ordinary chondrite parent bodies, complete disruption, and mixing possibly about 2.8 Gyr ago. Meteoritics and Planetary Science, 2024, 10.1111/maps.14193. hal-04612235

HAL Id: hal-04612235

https://hal.univ-brest.fr/hal-04612235

Submitted on 14 Jun 2024

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# The anomalous polymict ordinary chondrite breccia of Elmshorn (H3-6)-Late reaccretion after collision between two ordinary chondrite parent bodies, complete disruption, and mixing possibly about 2.8 Gyr ago

Addi Bischoff, Markus Patzek, Romain Alosius, Jean-Alix Barrat, Jasper Berndt, Henner Busemann, Detlev Degering, Tommaso Di Rocco, Mattias Ek, Jérôme Gattacceca, et al.

► To cite this version:

Addi Bischoff, Markus Patzek, Romain Alosius, Jean-Alix Barrat, Jasper Berndt, et al. The anomalous polymict ordinary chondrite breccia of Elmshorn (H3-6)-Late reaccretion after collision between two ordinary chondrite parent bodies, complete disruption, and mixing possibly about 2.8 Gyr ago. Meteoritics and Planetary Science, 2024, 10.1111/maps.14193. hal-04612235

HAL Id: hal-04612235

https://hal.univ-brest.fr/hal-04612235v1

Submitted on 14 Jun 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# The anomalous polymict ordinary chondrite breccia of Elmshorn (H3-6)—Late reaccretion after collision between two ordinary chondrite parent bodies, complete disruption, and mixing possibly about 2.8 Gyr ago

Addi BISCHOFF<sup>1,*</sup>, Markus PATZEK<sup>1</sup>, Romain M. L. ALOSIUS<sup>2</sup>, Jean-Alix BARRAT<sup>3,4</sup>, Jasper BERNDT<sup>5</sup>, Henner BUSEMANN<sup>2</sup>, Detlev DEGERING<sup>6</sup>, Tommaso DI ROCCO<sup>7</sup>, Mattias EK<sup>2</sup>, Jérôme GATTACCECA<sup>8</sup>, Jose R. A. GODINHO<sup>9</sup>, Dieter HEINLEIN<sup>10</sup>, Daniela KRIETSCH<sup>2</sup>, Colin MADEN<sup>2</sup>, Oscar MARCHHART<sup>11</sup>, Martin MARTSCHINI<sup>11</sup>, Silke MERCHEL<sup>11</sup>, Andreas PACK<sup>7</sup>, Stefan PETERS<sup>12</sup>, Miriam RÜFENACHT<sup>2</sup>, Jochen SCHLÜTER<sup>12</sup>, Maria SCHÖNBÄCHLER<sup>2</sup>, Aleksandra STOJIC<sup>1</sup>, Jakob STORZ<sup>1</sup>, Wolfgang TILLMANN<sup>13</sup>, Alexander WIESER<sup>11</sup>, Karl WIMMER<sup>14</sup>, and Reiner ZIELKE<sup>13</sup>

<sup>1</sup>Institut für Planetologie, University of Münster, Münster, Germany

<sup>2</sup>Institute of Geochemistry and Petrology, ETH Zürich, Zurich, Switzerland

<sup>3</sup>Univ Brest, CNRS, Ifremer, IRD, LEMAR, Institut Universitaire Européen de la Mer (IUEM), Place Nicolas Copernic, Plouzané, France

<sup>4</sup>Institut Universitaire de France, Paris, France

<sup>5</sup>Institut für Mineralogie, University of Münster, Münster, Germany

<sup>6</sup>VKTA—Strahlenschutz, Analytik & Entsorgung Rossendorf e. V., Dresden, Germany

<sup>7</sup>Geowissenschaftliches Zentrum, Universität Göttingen, Göttingen, Germany

<sup>8</sup>CNRS, Aix Marseille Univ, IRD, INRAE, CEREGE, Aix-en-Provence, France

<sup>9</sup>Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Freiberg, Germany

<sup>10</sup>German Fireball Network, Augsburg, Germany

<sup>11</sup>Faculty of Physics, Isotope Physics, University of Vienna, Vienna, Austria

<sup>12</sup>Museum der Natur Hamburg—Mineralogie, LIB, Hamburg, Germany

<sup>13</sup>RIF Institut für Forschung und Transfer e.V., Dortmund, Germany

<sup>14</sup>Salvatorgasse 12, Nördlingen, Germany

*Correspondence

Addi Bischoff, Institut für Planetologie, University of Münster, Wilhelm-Klemm-Str. 10, Münster D-48149, Germany.

Email: bischoa@uni-muenster.de

(Received 18 December 2023; revision accepted 06 May 2024)

**Abstract**—Elmshorn fell April 25, 2023, about 30 km northwest of the city of Hamburg (Germany). Shortly after the fall, 21 pieces were recovered totaling a mass of 4277 g. Elmshorn is a polymict and anomalous H3-6 chondritic, fragmental breccia. The rock is a mixture of typical H chondrite lithologies and clasts of intermediate H/L (or L, based on magnetic properties) chondrite origin. In some of the 21 pieces, the H chondrite lithologies dominate, while in others the H/L (or L) chondrite components are prevalent. The H/L chondrite assignment of these components is based on the mean composition of their olivines in equilibrated type 4 fragments (~Fa$_{21–22}$). The physical properties like density (3.34 g cm$^{-3}$) and magnetic susceptibility (log χ < 5.0, with χ in 10$^{-9}$ m$^{3}$ kg$^{-1}$) are typical for L chondrites, which is inconsistent with the oxygen isotope compositions: all eight O isotope analyses from two different fragments clearly fall into the H chondrite field. Thus, the fragments found in the strewn field vary in mineralogy, mineral chemistry, and physical properties but not in O isotope characteristics. The sample most intensively studied belongs to the stones dominated by H chondrite lithologies. The chemical composition and nucleosynthetic Cr and Ti isotope
# The anomalous polymict ordinary chondrite breccia of Elmshorn (H3-6)—Late reaccretion after collision between two ordinary chondrite parent bodies, complete disruption, and mixing possibly about 2.8 Gyr ago

Addi BISCHOFF<sup>1,*</sup>, Markus PATZEK<sup>1</sup>, Romain M. L. ALOSIUS<sup>2</sup>, Jean-Alix BARRAT<sup>3,4</sup>, Jasper BERNDT<sup>5</sup>, Henner BUSEMANN<sup>2</sup>, Detlev DEGERING<sup>6</sup>, Tommaso DI ROCCO<sup>7</sup>, Mattias EK<sup>2</sup>, Jérôme GATTACCECA<sup>8</sup>, Jose R. A. GODINHO<sup>9</sup>, Dieter HEINLEIN<sup>10</sup>, Daniela KRIETSCH<sup>2</sup>, Colin MADEN<sup>2</sup>, Oscar MARCHHART<sup>11</sup>, Martin MARTSCHINI<sup>11</sup>, Silke MERCHEL<sup>11</sup>, Andreas PACK<sup>7</sup>, Stefan PETERS<sup>12</sup>, Miriam RÜFENACHT<sup>2</sup>, Jochen SCHLÜTER<sup>12</sup>, Maria SCHÖNBÄCHLER<sup>2</sup>, Aleksandra STOJIC<sup>1</sup>, Jakob STORZ<sup>1</sup>, Wolfgang TILLMANN<sup>13</sup>, Alexander WIESER<sup>11</sup>, Karl WIMMER<sup>14</sup>, and Reiner ZIELKE<sup>13</sup>

*Correspondence

Addi Bischoff, Institut für Planetologie, University of Münster, Wilhelm-Klemm-Str. 10, Münster D-48149, Germany.

Email: bischoa@uni-muenster.de

*(Received 18 December 2023; revision accepted 06 May 2024)*

**Abstract**—Elmshorn fell April 25, 2023, about 30 km northwest of the city of Hamburg (Germany). Shortly after the fall, 21 pieces were recovered totaling a mass of 4277 g. Elmshorn is a polymict and anomalous H3-6 chondritic, fragmental breccia. The rock is a mixture of typical H chondrite lithologies and clasts of intermediate H/L (or L, based on magnetic properties) chondrite origin. In some of the 21 pieces, the H chondrite lithologies dominate, while in others the H/L (or L) chondrite components are prevalent. The H/L chondrite assignment of these components is based on the mean composition of their olivines in equilibrated type 4 fragments (~Fa$_{21-22}$). The physical properties like density (3.34 g cm$^{-3}$) and magnetic susceptibility (log χ < 5.0, with χ in 10$^{-9}$ m$^{3}$ kg$^{-1}$) are typical for L chondrites, which is inconsistent with the oxygen isotope compositions: all eight O isotope analyses from two different fragments clearly fall into the H chondrite field. Thus, the fragments found in the strewn field vary in mineralogy, mineral chemistry, and physical properties but not in O isotope characteristics. The sample most intensively studied belongs to the stones dominated by H chondrite lithologies. The chemical composition and nucleosynthetic Cr and Ti isotope

<footnote n="1"><sup>1</sup>Institut für Planetologie, University of Münster, Münster, Germany</footnote>

<footnote n="2"><sup>2</sup>Institute of Geochemistry and Petrology, ETH Zürich, Zurich, Switzerland</footnote>

<footnote n="3"><sup>3</sup>Univ Brest, CNRS, Ifremer, IRD, LEMAR, Institut Universitaire Européen de la Mer (IUEM), Place Nicolas Copernic, Plouzané, France</footnote>

<footnote n="4"><sup>4</sup>Institut Universitaire de France, Paris, France</footnote>

<footnote n="5"><sup>5</sup>Institut für Mineralogie, University of Münster, Münster, Germany</footnote>

<footnote n="6"><sup>6</sup>VKTA—Strahlenschutz, Analytik & Entsorgung Rossendorf e. V., Dresden, Germany</footnote>

<footnote n="7"><sup>7</sup>Geowissenschaftliches Zentrum, Universität Göttingen, Göttingen, Germany</footnote>

<footnote n="8"><sup>8</sup>CNRS, Aix Marseille Univ, IRD, INRAE, CEREGE, Aix-en-Provence, France</footnote>

<footnote n="9"><sup>9</sup>Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Freiberg, Germany</footnote>

<footnote n="10"><sup>10</sup>German Fireball Network, Augsburg, Germany</footnote>

<footnote n="11"><sup>11</sup>Faculty of Physics, Isotope Physics, University of Vienna, Vienna, Austria</footnote>

<footnote n="12"><sup>12</sup>Museum der Natur Hamburg—Mineralogie, LIB, Hamburg, Germany</footnote>

<footnote n="13"><sup>13</sup>RIF Institut für Forschung und Transfer e.V., Dortmund, Germany</footnote>

<footnote n="14"><sup>14</sup>Salvatorgasse 12, Nördlingen, Germany</footnote>
data are typical for ordinary chondrites. The noble gases in Elmshorn represent a mixture between cosmogenic, radiogenic, and primordially trapped noble gases, while a solar wind component can be excluded. Because the chondritic rock of Elmshorn contains (a) H chondrite parent body interior materials (of types 5 and 6), (b) chondrite parent body near-surface materials (of types 3 and 4), (c) fragments of an H/L chondrite (dominant in many stones), (d) shock-darkened fragments, and (e) clasts of various types of impact melts but no solar wind-implanted noble gases, the different components cannot have been part of a parent body regolith. The most straightforward explanation is that the fragmental breccia of Elmshorn represents a reaccreted rock after a catastrophic collision between an H chondrite parent body and another body with H/L (or L) chondrite characteristics but with deviating O isotope values (i.e. that of H chondrites), complete disruption of the bodies, mixing, and reassembly. This is the only straightforward way that the implantation of solar wind gases could have been avoided in this kind of complex breccia. The gas retention ages of about 2.8 Gyr possibly indicate the closure time after the catastrophic collision between H and H/L (or L) chondrite parent bodies, while the cosmic ray exposure age for Elmshorn, which had areatmospheric radius of 25–40 cm, is ~17–20 Myr.

INTRODUCTION

Due to catastrophic collisions between asteroids and smaller impacts on solar system bodies, different processes can lead to the modification of meteorite parent bodies, the formation of new bodies, and the emergence of new rock types. These processes include, for example, accretion, excavation of material, thermal metamorphism, reduction processes, melting, mixing of different material, reaccretion, and relithification (e.g., Bischoff et al., 2006, 2018; Keil, 1982; Rubin & Turrin, 2023). All these processes can be repeated many times and may lead to complex meteorite breccias that contain a large variety of fragments and lithologies, which is also the case for Elmshorn.

Elmshorn fell April 25, 2023, about 30 km northwest of the city of Hamburg (Germany). The daytime fireball at 12:14:24 UT was recorded for a duration of 3 s by two meteor cameras of the Allsky7 network and observed by eyewitnesses in northern Germany and the Netherlands (https://fma.imo.net). Exactly 117 s after the bolide appeared, a 3731 g stony meteorite struck an Elmshorn garden on Irena-Sendler-Strasse and penetrated 30–40 cm deep into the ground (sample E01; Table S1). The impact was acoustically recorded by a nearby surveillance camera. Shortly thereafter, smaller pieces hit the roofs of two Elmshorn homes, damaging several roof tiles. Intensive search activities led to the discovery of complete meteorite pieces or their fragments at another 18 locations in the northern city area of Elmshorn. Details about the recovered 21 pieces are given in Table S1. Besides the main mass mentioned before, one of the first recognized pieces of 233.5 g (E02) crashed into the roof of a house on the street Iltisweg. Another large piece of about 156 g (E03) broke into many pieces after strongly impacting the roof

of a house on Gärtnerstrasse. Some examples are shown in Figure 1. The finding that these are fresh meteorite samples is supported by short-lived cosmogenic radionuclide detection by gamma spectrometry in E01 and E02. The presence of short-lived cosmogenic radionuclides with half-lives as short as 5.6 days proves that the fallen and recovered object was recently exposed to cosmic rays in space, linking it clearly to the bolide event. Elmshorn has been classified as a polymict H3-6 chondritic breccia (The Meteoritical Bulletin, 2023). The first rock studied in detail (E03) mainly contains H chondrite lithologies but also abundant clasts of intermediate H/L (or L) chondrite heritage. A second individual sample (E07) from the strewn field studied for comparison shows abundant fragments of H/L (or L) chondrite origin.

In central Europe, 11 meteorite falls (including Elmshorn) have been recovered in an area less than 500 km in radius in the last 10 years. Ten falls were found to be ordinary chondrites (OCs), while only one (Flensburg) represents a small extraordinary C1 chondrite of 24 g (The Meteoritical Bulletin, 2023). Remarkably, the two most scientifically interesting samples, namely Flensburg and Elmshorn, fell only 110 km apart within a period of only 4 years.

SAMPLES, ANALYTICAL PROCEDURES, MODEL CONSIDERATIONS, AND THE FIND LOCATIONS OF THE ELMSHORN METEORITE

Studied Samples

In the days following the meteorite fall, 21 individual meteorite samples were recovered within a strewn field of about 1.5 × 2.5 km² (Figure 2). Images of typical locations of the find area are given in Figure 3.
data are typical for ordinary chondrites. The noble gases in Elmshorn represent a mixture between cosmogenic, radiogenic, and primordially trapped noble gases, while a solar wind component can be excluded. Because the chondritic rock of Elmshorn contains (a) H chondrite parent body interior materials (of types 5 and 6), (b) chondrite parent body near-surface materials (of types 3 and 4), (c) fragments of an H/L chondrite (dominant in many stones), (d) shock-darkened fragments, and (e) clasts of various types of impact melts but no solar wind-implanted noble gases, the different components cannot have been part of a parent body regolith. The most straightforward explanation is that the fragmental breccia of Elmshorn represents a reaccreted rock after a catastrophic collision between an H chondrite parent body and another body with H/L (or L) chondrite characteristics but with deviating O isotope values (i.e. that of H chondrites), complete disruption of the bodies, mixing, and reassembly. This is the only straightforward way that the implantation of solar wind gases could have been avoided in this kind of complex breccia. The gas retention ages of about 2.8 Gyr possibly indicate the closure time after the catastrophic collision between H and H/L (or L) chondrite parent bodies, while the cosmic ray exposure age for Elmshorn, which had areatmospheric radius of 25–40 cm, is ~17–20 Myr.

INTRODUCTION

Due to catastrophic collisions between asteroids and smaller impacts on solar system bodies, different processes can lead to the modification of meteorite parent bodies, the formation of new bodies, and the emergence of new rock types. These processes include, for example, accretion, excavation of material, thermal metamorphism, reduction processes, melting, mixing of different material, reaccretion, and relithification (e.g., Bischoff et al., 2006, 2018; Keil, 1982; Rubin & Turrin, 2023). All these processes can be repeated many times and may lead to complex meteorite breccias that contain a large variety of fragments and lithologies, which is also the case for Elmshorn.

Elmshorn fell April 25, 2023, about 30 km northwest of the city of Hamburg (Germany). The daytime fireball at 12:14:24 UT was recorded for a duration of 3 s by two meteor cameras of the Allsky7 network and observed by eyewitnesses in northern Germany and the Netherlands (https://fma.imo.net). Exactly 117 s after the bolide appeared, a 3731 g stony meteorite struck an Elmshorn garden on Irena-Sendler-Strasse and penetrated 30–40 cm deep into the ground (sample E01; Table S1). The impact was acoustically recorded by a nearby surveillance camera. Shortly thereafter, smaller pieces hit the roofs of two Elmshorn homes, damaging several roof tiles. Intensive search activities led to the discovery of complete meteorite pieces or their fragments at another 18 locations in the northern city area of Elmshorn. Details about the recovered 21 pieces are given in Table S1. Besides the main mass mentioned before, one of the first recognized pieces of 233.5 g (E02) crashed into the roof of a house on the street Iltisweg. Another large piece of about 156 g (E03) broke into many pieces after strongly impacting the roof

of a house on Gärtnerstrasse. Some examples are shown in Figure 1. The finding that these are fresh meteorite samples is supported by short-lived cosmogenic radionuclide detection by gamma spectrometry in E01 and E02. The presence of short-lived cosmogenic radionuclides with half-lives as short as 5.6 days proves that the fallen and recovered object was recently exposed to cosmic rays in space, linking it clearly to the bolide event. Elmshorn has been classified as a polymict H3-6 chondritic breccia (The Meteoritical Bulletin, 2023). The first rock studied in detail (E03) mainly contains H chondrite lithologies but also abundant clasts of intermediate H/L (or L) chondrite heritage. A second individual sample (E07) from the strewn field studied for comparison shows abundant fragments of H/L (or L) chondrite origin.

In central Europe, 11 meteorite falls (including Elmshorn) have been recovered in an area less than 500 km in radius in the last 10 years. Ten falls were found to be ordinary chondrites (OCs), while only one (Flensburg) represents a small extraordinary C1 chondrite of 24 g (The Meteoritical Bulletin, 2023). Remarkably, the two most scientifically interesting samples, namely Flensburg and Elmshorn, fell only 110 km apart within a period of only 4 years.

SAMPLES, ANALYTICAL PROCEDURES, MODEL CONSIDERATIONS, AND THE FIND LOCATIONS OF THE ELMSHORN METEORITE

Studied Samples

In the days following the meteorite fall, 21 individual meteorite samples were recovered within a strewn field of about 1.5 × 2.5 km² (Figure 2). Images of typical locations of the find area are given in Figure 3.
<figure><img src="image_2.png" /></figure>

FIGURE 1. Images of six (of the total 21) Elmshorn stony meteorites found between April 25 and May 29, 2023. (a) The E01 (Table S1), weighing 3731 g, struck a garden and made a hole in the lawn 30–40 cm deep. (b) An individual piece of Elmshorn, E02, weighing 233.5 g, hit the roof of a house, was recovered within a few minutes, and felt hand-warm, as reported by the finder. (c) Piece E11, at 7.98 g, has a dull black fusion crust and a broken edge. (d) This broken meteorite fragment, E15, weighing 3.40 g, was discovered on the grassy side of a road. (e) This complete chondrite specimen E18, weighing 2.43 g, was found lying in the moss at the Elmshorn cemetery. (f) The smallest recovered complete piece, E21, of 1.09 g, hit the terrace of a house in Elmshorn; the fusion-crusted surface of the meteorite shows its flight orientation and a metal inclusion.
<figure><img src="image_3.png" /></figure>

FIGURE 1. Images of six (of the total 21) Elmshorn stony meteorites found between April 25 and May 29, 2023. (a) The E01 (Table S1), weighing 3731 g, struck a garden and made a hole in the lawn 30–40 cm deep. (b) An individual piece of Elmshorn, E02, weighing 233.5 g, hit the roof of a house, was recovered within a few minutes, and felt hand-warm, as reported by the finder. (c) Piece E11, at 7.98 g, has a dull black fusion crust and a broken edge. (d) This broken meteorite fragment, E15, weighing 3.40 g, was discovered on the grassy side of a road. (e) This complete chondrite specimen E18, weighing 2.43 g, was found lying in the moss at the Elmshorn cemetery. (f) The smallest recovered complete piece, E21, of 1.09 g, hit the terrace of a house in Elmshorn; the fusion-crusted surface of the meteorite shows its flight orientation and a metal inclusion.
<figure><img src="image_3.png" /></figure>

FIGURE 2. Locations and distribution of the meteorites: From April 25 to May 29, 2023, stony meteorites were found at 21 different locations in the northern part of the city of Elmshorn: The 3731 g main mass (E01) is marked by a magenta dot (upper left). Red dots represent two specimens in the range of 100–1000 g, and orange dots represent three pieces weighing 10–100 g. The 15 small meteorite finds (1–10 g) are marked in yellow and were mostly found in an area northeast of the railway tracks. The two samples studied in more detail are marked by arrows. Samples E01 and E02 were used for nondestructive gamma spectrometry. Source of base map: Google Earth.

The first studied fragment of Elmshorn was recovered April 26, 2023 (1 day after the fall). From the scattered (in total 156 g; E03) piece, a sample of 20.5 g was used for classification procedures. We crushed about 0.6 g to reveal a coarse-grained, relatively homogeneous powder. This powder still contained large (>0.5 mm) particles due to many large metal-sulfide associations present in the samples that are difficult to destroy. Four thin sections of the rock (fragment E03; PL23028, PL23029, PL23030, PL23031), with an area of ~3.5 cm² each, were available for optical and electron microscopic studies. For comparison, a second sample from E07 was studied in a polished section (PL23047) of ~0.75 cm², and small pieces of E07 were used for additional analyses of oxygen isotopes and magnetic susceptibility (MS). This sample was found about 1 month after the fall on May 27, 2023.

# Analytical Procedures and Model Considerations

## Mineralogical Studies

At the Institut für Planetologie (University of Münster), an Axiophot polarizing microscope (Fa. ZEISS) was used for optical microscopy in transmitted and reflected light. At the same institution, a JEOL 6610-LV electron microscope (SEM) was used to study the brecciated texture of the Elmshorn samples and to identify

the different mineral phases. Some chemical data were obtained using the INCA analytical program provided by Oxford Instruments for energy-dispersive spectrometry.

Most quantitative mineral analyses were obtained with a JEOL JXA 8530F electron microprobe at the Institut für Mineralogie (University of Münster), which was operated at 15 kV and a probe current of 15 nA. Synthetic and natural standards were used for wavelength-dispersive spectrometry. As standards for mineral analyses, we used jadeite (Na), San Carlos olivine (Mg), kyanite (Al), hypersthene (Si), sanidine (K), chromium oxide (Cr), diopside (Ca), rhodonite (Mn), rutile (Ti), fayalite (Fe), apatite (P), celestine (S), Co metal (Co), and nickel oxide (Ni). We have checked the peak situation and found no overlap of the Fe-Kβ peak on the Co-Kα peak.

## Bulk Chemical Analysis

From the crushed and homogenized material from fragment E03, about 180 mg was used for bulk chemical analyses at the University of Brest. The chemical bulk composition of Elmshorn was obtained using inductively coupled plasma atomic emission spectrometry (ICP-AES; for Fe, Mn, Mg, Na, Cr, Co, and Ni) and inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The concentration reproducibility is generally
<figure><img src="image_4.png" /></figure>

FIGURE 2. Locations and distribution of the meteorites: From April 25 to May 29, 2023, stony meteorites were found at 21 different locations in the northern part of the city of Elmshorn: The 3731 g main mass (E01) is marked by a magenta dot (upper left). Red dots represent two specimens in the range of 100–1000 g, and orange dots represent three pieces weighing 10–100 g. The 15 small meteorite finds (1–10 g) are marked in yellow and were mostly found in an area northeast of the railway tracks. The two samples studied in more detail are marked by arrows. Samples E01 and E02 were used for nondestructive gamma spectrometry. Source of base map: Google Earth.

The first studied fragment of Elmshorn was recovered April 26, 2023 (1 day after the fall). From the scattered (in total 156 g; E03) piece, a sample of 20.5 g was used for classification procedures. We crushed about 0.6 g to reveal a coarse-grained, relatively homogeneous powder. This powder still contained large (>0.5 mm) particles due to many large metal-sulfide associations present in the samples that are difficult to destroy. Four thin sections of the rock (fragment E03; PL23028, PL23029, PL23030, PL23031), with an area of ~3.5 cm² each, were available for optical and electron microscopic studies. For comparison, a second sample from E07 was studied in a polished section (PL23047) of ~0.75 cm², and small pieces of E07 were used for additional analyses of oxygen isotopes and magnetic susceptibility (MS). This sample was found about 1 month after the fall on May 27, 2023.

## Analytical Procedures and Model Considerations

### Mineralogical Studies

At the Institut für Planetologie (University of Münster), an Axiophot polarizing microscope (Fa. ZEISS) was used for optical microscopy in transmitted and reflected light. At the same institution, a JEOL 6610-LV electron microscope (SEM) was used to study the brecciated texture of the Elmshorn samples and to identify

the different mineral phases. Some chemical data were obtained using the INCA analytical program provided by Oxford Instruments for energy-dispersive spectrometry.

Most quantitative mineral analyses were obtained with a JEOL JXA 8530F electron microprobe at the Institut für Mineralogie (University of Münster), which was operated at 15 kV and a probe current of 15 nA. Synthetic and natural standards were used for wavelength-dispersive spectrometry. As standards for mineral analyses, we used jadeite (Na), San Carlos olivine (Mg), kyanite (Al), hypersthene (Si), sanidine (K), chromium oxide (Cr), diopside (Ca), rhodonite (Mn), rutile (Ti), fayalite (Fe), apatite (P), celestine (S), Co metal (Co), and nickel oxide (Ni). We have checked the peak situation and found no overlap of the Fe-Kβ peak on the Co-Kα peak.

### Bulk Chemical Analysis

From the crushed and homogenized material from fragment E03, about 180 mg was used for bulk chemical analyses at the University of Brest. The chemical bulk composition of Elmshorn was obtained using inductively coupled plasma atomic emission spectrometry (ICP-AES; for Fe, Mn, Mg, Na, Cr, Co, and Ni) and inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The concentration reproducibility is generally
<figure><img src="image_4.png" /><figcaption>FIGURE 3. (a) Small forest in the north of Elmshorn on Kaltenhof street, close to the place where sample E04 (Table S1) was found; (b) area in the northwestern part of the strewn field close to the find location of the 3.7 kg piece (E01); (c) grain field west of the Irena-Sendler city area of Elmshorn; (d) view into the street Iltisweg, where the 233.5 g (E02) sample crashed onto a roof; (e) north of the railway tracks, samples were searched for by a drone; (f) a grassland east of Iltisweg and north of the railway tracks after the grass was cut in early June.</figcaption></figure>
<figure><img src="image_5.png" /></figure>

FIGURE 3. (a) Small forest in the north of Elmshorn on Kaltenhof street, close to the place where sample E04 (Table S1) was found; (b) area in the northwestern part of the strewn field close to the find location of the 3.7 kg piece (E01); (c) grain field west of the Irena-Sendler city area of Elmshorn; (d) view into the street Iltisweg, where the 233.5 g (E02) sample crashed onto a roof; (e) north of the railway tracks, samples were searched for by a drone; (f) a grassland east of Iltisweg and north of the railway tracks after the grass was cut in early June.
greater than 5%. Further details concerning the analytical method are reported by Barrat et al. (2012, 2016).

## Oxygen Isotope Analyses

Measuring the oxygen isotope composition is an important tool for classifying meteorites (e.g., Clayton et al., 1976). For Elmshorn, the compositions of eight chips (each weighing between 2.0 and 2.3 mg) from two recovered pieces (E03 and E07) were obtained by means of laser fluorination in combination with a gas source mass spectrometer. The analytical techniques are given in detail in Pack et al. (2016) and Peters et al. (2020; also, compare Herwartz et al. 2014; Pack & Herwartz, 2014; Pack et al., 2017). The δ¹⁷O and δ¹⁸O values are reported on the VSMOW (Vienna Standard Mean Ocean Water) scale, and the Δ¹⁷O is defined here as:

$$ \Delta^{17}\text{O} = 1000 \ln\left(\frac{\delta^{17}\text{O}}{1000} + 1\right) - 0.528 \\ \times 1000 \ln\left(\frac{\delta^{18}\text{O}}{1000} + 1\right). $$

To anchor δ¹⁷O on the VSMOW scale, we used a Δ¹⁷O value for San Carlos olivine of -0.052‰ (average value of Pack et al., 2016; Sharp et al., 2016; Wostbrock et al., 2020). In this study, the estimated measurement uncertainties are ±0.1‰ for δ¹⁸O and ±0.01‰ for Δ¹⁷O, and these data are based on replicate analyses of the San Carlos olivine standard (1 SD).

## Titanium and Chromium Isotope Analysis

For nucleosynthetic Ti and Cr isotope analyses of the Elmshorn meteorite, 28.66 mg of powdered material from E03 was used. The powder was dissolved in octagonal Savillex® vials following the procedure in Bischoff, Barrat, et al. (2019). Titanium was separated and purified in a three-step anion exchange chromatography procedure as described in Williams et al. (2021). Chromium was separated from the matrix fraction of the first Ti ion exchange procedure using a two-step cation exchange procedure described in Bischoff, Barrat, et al. (2019). The blank of the full chemical procedure was 1.7 ng Ti and 20 ng Cr. This corresponds to a blank contribution of maximum 0.014% for Ti and 0.027% for Cr.

The Ti isotope analyses were performed on a Thermo Scientific Neptune Plus multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS) at ETH Zurich, following the description in Rüfenacht et al. (2023). The measurements were done in medium mass resolution (MR) with a mass resolving power R ~ 6500 (R = m/[m₀.95-m₀.05]). One single measurement consumed ~0.5 µg Ti and achieved a signal of ~40 V over a 10¹¹ Ohm resistor on ⁴⁸Ti. The isotope data were

corrected for instrumental mass bias by normalizing to the ⁴⁹Ti/⁴⁷Ti ratio of 0.749766 (Niederer et al., 1985), using the exponential law. The data are reported relative to an in-house Alfa Aesar Ti wire standard in the ε notation and applying the sample-standard bracketing method:

$$ \varepsilon^i \text{Ti} = \left( \frac{i/47 \text{Ti}_{\text{sample}}}{i/47 \text{Ti}_{\text{standard}}} - 1 \right) \times 10^4, $$

where i stands for the isotope masses ⁴⁶Ti, ⁴⁸Ti, and ⁵⁰Ti. The isotope data were collected on four different days and include 10 repeat measurement for Elmshorn. Parallel to the Elmshorn meteorite, the terrestrial rock standard BHVO-2 and the OC Forest Vale (H4) were measured to assess the accuracy and reproducibility of the measurements.

Chromium isotope analyses were also performed at ETH Zurich on a Thermo Scientific Neptune Plus MC-ICP-MS following the procedure outlined in Rüfenacht et al. (2023). All measurements were performed in medium resolution with a typical resolving power of R ~ 6500. Approximately 0.5 µg Cr was consumed for a single measurement which corresponded to a signal of ~110 V on ⁵²Cr. Instrumental mass fractionation was corrected relative to ⁵⁰Cr/⁵²Cr = 0.051859 (Shields et al., 1966) using the exponential law. Sample measurements were bracketed with measurements of the NIST SRM 979 standard and Cr isotope data are reported in ε notation relative to these standards:

$$ \varepsilon^i \text{Cr} = \left( \frac{i/52 \text{Cr}_{\text{sample}}}{i/52 \text{Cr}_{\text{standard}}} - 1 \right) \times 10^4, $$

where i stands for the isotope masses ⁵³Cr and ⁵⁴Cr. Elmshorn was measured six times in three different analytical sessions. In addition to Elmshorn, the terrestrial rock standard DTS-2 was measured in all sessions to monitor the accuracy and reproducibility of the measurements.

## Noble Gas Mass Spectrometry

All stable noble gas isotopes (He-Xe) were measured on two aliquots of 15.307 ± 0.023 mg (“Elmshorn 1”) and 15.090 ± 0.026 mg (“Elmshorn 2”) from stone E03 (Table S1). The aliquots were wrapped in aluminum foil and heated to 110°C for several days in a sample chamber to degas adsorbed atmospheric gases. The measurements were performed on the in-house built noble gas mass spectrometer called Albatros at ETH Zürich following procedures further described in Riebe et al. (2017). The noble gases were extracted in a Mo crucible by heating the samples to ~1700°C for ~25 min. Blank corrections
greater than 5%. Further details concerning the analytical method are reported by Barrat et al. (2012, 2016).

## Oxygen Isotope Analyses

Measuring the oxygen isotope composition is an important tool for classifying meteorites (e.g., Clayton et al., 1976). For Elmshorn, the compositions of eight chips (each weighing between 2.0 and 2.3 mg) from two recovered pieces (E03 and E07) were obtained by means of laser fluorination in combination with a gas source mass spectrometer. The analytical techniques are given in detail in Pack et al. (2016) and Peters et al. (2020; also, compare Herwartz et al. 2014; Pack & Herwartz, 2014; Pack et al., 2017). The δ¹⁷O and δ¹⁸O values are reported on the VSMOW (Vienna Standard Mean Ocean Water) scale, and the Δ¹⁷O is defined here as:

$$ \Delta^{17}\text{O} = 1000 \ln\left(\frac{\delta^{17}\text{O}}{1000} + 1\right) - 0.528 \times 1000 \ln\left(\frac{\delta^{18}\text{O}}{1000} + 1\right). $$

To anchor δ¹⁷O on the VSMOW scale, we used a Δ¹⁷O value for San Carlos olivine of -0.052‰ (average value of Pack et al., 2016; Sharp et al., 2016; Wostbrock et al., 2020). In this study, the estimated measurement uncertainties are ±0.1‰ for δ¹⁸O and ±0.01‰ for Δ¹⁷O, and these data are based on replicate analyses of the San Carlos olivine standard (1 SD).

## Titanium and Chromium Isotope Analysis

For nucleosynthetic Ti and Cr isotope analyses of the Elmshorn meteorite, 28.66 mg of powdered material from E03 was used. The powder was dissolved in octagonal Savillex® vials following the procedure in Bischoff, Barrat, et al. (2019). Titanium was separated and purified in a three-step anion exchange chromatography procedure as described in Williams et al. (2021). Chromium was separated from the matrix fraction of the first Ti ion exchange procedure using a two-step cation exchange procedure described in Bischoff, Barrat, et al. (2019). The blank of the full chemical procedure was 1.7 ng Ti and 20 ng Cr. This corresponds to a blank contribution of maximum 0.014% for Ti and 0.027% for Cr.

The Ti isotope analyses were performed on a Thermo Scientific Neptune Plus multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS) at ETH Zurich, following the description in Rüfenacht et al. (2023). The measurements were done in medium mass resolution (MR) with a mass resolving power R ~ 6500 (R = m/[m₀.95-m₀.05]). One single measurement consumed ~0.5 µg Ti and achieved a signal of ~40 V over a 10¹¹ Ohm resistor on ⁴⁸Ti. The isotope data were

corrected for instrumental mass bias by normalizing to the ⁴⁹Ti/⁴⁷Ti ratio of 0.749766 (Niederer et al., 1985), using the exponential law. The data are reported relative to an in-house Alfa Aesar Ti wire standard in the ε notation and applying the sample-standard bracketing method:

$$ \epsilon^i \text{Ti} = \left( \frac{i/47 \text{Ti}_{\text{sample}}}{i/47 \text{Ti}_{\text{standard}}} - 1 \right) \times 10^4, $$

where i stands for the isotope masses ⁴⁶Ti, ⁴⁸Ti, and ⁵⁰Ti. The isotope data were collected on four different days and include 10 repeat measurement for Elmshorn. Parallel to the Elmshorn meteorite, the terrestrial rock standard BHVO-2 and the OC Forest Vale (H4) were measured to assess the accuracy and reproducibility of the measurements.

Chromium isotope analyses were also performed at ETH Zurich on a Thermo Scientific Neptune Plus MC-ICP-MS following the procedure outlined in Rüfenacht et al. (2023). All measurements were performed in medium resolution with a typical resolving power of R ~ 6500. Approximately 0.5 µg Cr was consumed for a single measurement which corresponded to a signal of ~110 V on ⁵²Cr. Instrumental mass fractionation was corrected relative to ⁵⁰Cr/⁵²Cr = 0.051859 (Shields et al., 1966) using the exponential law. Sample measurements were bracketed with measurements of the NIST SRM 979 standard and Cr isotope data are reported in ε notation relative to these standards:

$$ \epsilon^i \text{Cr} = \left( \frac{i/52 \text{Cr}_{\text{sample}}}{i/52 \text{Cr}_{\text{standard}}} - 1 \right) \times 10^4, $$

where i stands for the isotope masses ⁵³Cr and ⁵⁴Cr. Elmshorn was measured six times in three different analytical sessions. In addition to Elmshorn, the terrestrial rock standard DTS-2 was measured in all sessions to monitor the accuracy and reproducibility of the measurements.

## Noble Gas Mass Spectrometry

All stable noble gas isotopes (He-Xe) were measured on two aliquots of 15.307 ± 0.023 mg (“Elmshorn 1”) and 15.090 ± 0.026 mg (“Elmshorn 2”) from stone E03 (Table S1). The aliquots were wrapped in aluminum foil and heated to 110°C for several days in a sample chamber to degas adsorbed atmospheric gases. The measurements were performed on the in-house built noble gas mass spectrometer called Albatros at ETH Zürich following procedures further described in Riebe et al. (2017). The noble gases were extracted in a Mo crucible by heating the samples to ~1700°C for ~25 min. Blank corrections
for Elmshorn 1 and 2 are <0.4% of the He and Ne isotope signals, <4.9% for Ar, and <1.7% of the signals for all Kr and Xe isotopes.

## Instrumental Accelerator Mass Spectrometry for Cosmogenic $^{26}$Al and $^{41}$Ca

Accelerator mass spectrometry (AMS) is the method of choice for the detection of long-lived cosmogenic radionuclides such as $^{26}$Al and $^{41}$Ca ($t_{1/2} = 0.705$ and 0.104 Myr, respectively; Norris et al., 1983; Paul et al., 1991). Recently, a worldwide unique development at the Vienna Environmental Research Accelerator (VERA), an ion-laser interaction mass spectrometry (ILIAMS) system allows the isobar suppression by up to 14 orders of magnitude (Martschini et al., 2022). Hence, ILIAMS-assisted AMS, so-called instrumental AMS (IAMS), enables now the direct detection of $^{26}$Al/$^{27}$Al (~$10^{-10}$) and $^{41}$Ca/$^{40}$Ca (~$10^{-12}$) in crushed Elmshorn containing intrinsic ~1% Al and Ca. Isobars from the natively abundant elements (12.6% Mg, 1‰ K) do not cause any analysis problem making radiochemical separation redundant. IAMS was performed on an additionally crushed aliquot (~75 mg) of the 0.6 g powder of E03. For $AlO^{-}$ extraction and $^{26}$Al/$^{27}$Al measurements (Lachner et al., 2021), a small portion of the fine-grained powder was pressed without any metal binder in Cu cathodes. For $^{41}$Ca/$^{40}$Ca ~1 mg powder was mixed with ~9 mg of $PbF_{2}$ to increase $CaF_{3}^{-}$ extraction from the Cs ion sputter source and finally also pressed in Cu cathodes. In-house standards "Dhurmsala" ($^{26}$Al/$^{27}$Al = [1.287 ± 0.0341]× $10^{-10}$) and SMD-Ca-12, traceable to primary standards (Rugel et al., 2016), have been used for normalization. IAMS data total uncertainties include counting statistics and scatter for each sample, the variability of the measurements of the standards and the uncertainty of the nominal value of the standard material. For transformation of nuclide ratios into specific activities in disintegration per minute (dpm) per kg, Al and Ca concentrations of Table S2 (1.13% Al; 1.08% Ca) have been used. For comparison of these specific activities measured by IAMS with Monte Carlo calculation based radius- and depth-dependent production rates (Leya & Masarik, 2009), additional values of Table S2 with data from Alexander (2019) and Lodders and Fegley (1998) have been used as input parameters.

## Considerations Concerning Cosmogenic Nuclides

Helium is purely cosmogenic (cos) except for additional radiogenic (rad) $^{4}$He. The former correlates with the lack of evidence for a Ne-trapped (tr) component. Thus, we can exclude the presence of a solar wind component. The $^{36}$Ar/$^{38}$Ar values for both samples (3.498 ± 0.022 for Elmshorn 1 and 3.458 ± 0.017 for Elmshorn 2) do not match pure cosmogenic compositions

(0.63–0.67; Wieler, 2002); this implies mixing between trapped and cosmogenic Ar, which were separated with a two-component deconvolution between ($^{36}$Ar/$^{38}$Ar)cos and ($^{36}$Ar/$^{38}$Ar)tr. In the absence of solar wind He and Ne, the trapped component used in the deconvolution was constrained between the values for Q and air (5.32–5.34; Busemann et al., 2000; Nier, 1950).

## Production Rates and Cosmic Ray Exposure Ages

In order to calculate the cosmic ray exposure (CRE) age, the production rates of cosmogenic $^{3}$He, $^{21}$Ne, and $^{38}$Ar must first be determined. This was done by using the model for OCs from Leya and Masarik (2009). This model takes into account the preatmospheric size of the meteoroid, the depth of the sample within the meteoroid, and the bulk chemical composition of the sample (see next). Both meteoroid size and sample depth are constrained using the measured purely cosmogenic $^{22}$Ne/$^{21}$Ne ratios as a shielding factor. A single production rate was defined from the two aliquots because their $^{22}$Ne/$^{21}$Ne ratios overlap within error (see next; Noble Gas Composition Section). The error-weighted mean of the two $^{22}$Ne/$^{21}$Ne ratios from Elmshorn 1 and 2 (1.1112 ± 0.0038) yielded several matches with the model predictions, ranging from radii of 25–500 cm. While the matches were mostly contained within depths of 6–10 cm for the lower radii, they shifted toward the center of the meteoroid at a radius of 120 cm. These deeper positions are statistically highly unlikely to host the sample (Mertens et al., 2021). Given the amount of material found, we also estimate that it would be unrealistic for the meteoroid to have exceeded a radius of 50 cm. For example, given a density of 3.448 g cm$^{-3}$ for fragment E03 (see next; Density Measurements Section) and if only 1% (in this case, the totally found mass of 4277 g) of the preatmospheric material had survived atmospheric entry, the radius of the meteoroid would have been ~30 cm. We consider this 99% ablation thought experiment to be an uncommon case, knowing that the average ablation for OCs with a radius ≤60 cm is of 91.5% of the preatmospheric material (Alexeev, 2003). The hypothesis of a relatively small preatmospheric radius along with our derived depths of samples match well with the values measured for $^{26}$Al and $^{60}$Co (see below in Further Short- and Long-Lived Radionuclides by Gamma Spectrometry Section; Alexeev et al., 2001; Kohout et al., 2017), which allows us to set an upper value for the radius at 50 cm. The derived meteoroid size, depth of samples, and production rates are given in Cosmic Ray Exposure Ages Section.

## U/Th-He and K-Ar Gas Retention Ages

The gas retention ages for Elmshorn 1 and 2 were calculated with both U/Th-He and K-Ar chronometers, with the U, Th, and K values measured on the
for Elmshorn 1 and 2 are <0.4% of the He and Ne isotope signals, <4.9% for Ar, and <1.7% of the signals for all Kr and Xe isotopes.

## Instrumental Accelerator Mass Spectrometry for Cosmogenic $^{26}$Al and $^{41}$Ca

Accelerator mass spectrometry (AMS) is the method of choice for the detection of long-lived cosmogenic radionuclides such as $^{26}$Al and $^{41}$Ca ($t_{1/2} = 0.705$ and 0.104 Myr, respectively; Norris et al., 1983; Paul et al., 1991). Recently, a worldwide unique development at the Vienna Environmental Research Accelerator (VERA), an ion-laser interaction mass spectrometry (ILIAMS) system allows the isobar suppression by up to 14 orders of magnitude (Martschini et al., 2022). Hence, ILIAMS-assisted AMS, so-called instrumental AMS (IAMS), enables now the direct detection of $^{26}$Al/$^{27}$Al ($\sim 10^{-10}$) and $^{41}$Ca/$^{40}$Ca ($\sim 10^{-12}$) in crushed Elmshorn containing intrinsic $\sim 1\%$ Al and Ca. Isobars from the natively abundant elements (12.6% Mg, 1‰ K) do not cause any analysis problem making radiochemical separation redundant. IAMS was performed on an additionally crushed aliquot ($\sim 75$ mg) of the 0.6 g powder of E03. For $AlO^{-}$ extraction and $^{26}$Al/$^{27}$Al measurements (Lachner et al., 2021), a small portion of the fine-grained powder was pressed without any metal binder in Cu cathodes. For $^{41}$Ca/$^{40}$Ca $\sim 1$ mg powder was mixed with $\sim 9$ mg of $PbF_{2}$ to increase $CaF_{3}^{-}$ extraction from the Cs ion sputter source and finally also pressed in Cu cathodes. In-house standards "Dhurmsala" ($^{26}$Al/$^{27}$Al = [1.287 $\pm$ 0.0341]$\times$ $10^{-10}$) and SMD-Ca-12, traceable to primary standards (Rugel et al., 2016), have been used for normalization. IAMS data total uncertainties include counting statistics and scatter for each sample, the variability of the measurements of the standards and the uncertainty of the nominal value of the standard material. For transformation of nuclide ratios into specific activities in disintegration per minute (dpm) per kg, Al and Ca concentrations of Table S2 (1.13% Al; 1.08% Ca) have been used. For comparison of these specific activities measured by IAMS with Monte Carlo calculation based radius- and depth-dependent production rates (Leya & Masarik, 2009), additional values of Table S2 with data from Alexander (2019) and Lodders and Fegley (1998) have been used as input parameters.

## Considerations Concerning Cosmogenic Nuclides

Helium is purely cosmogenic (cos) except for additional radiogenic (rad) $^{4}$He. The former correlates with the lack of evidence for a Ne-trapped (tr) component. Thus, we can exclude the presence of a solar wind component. The $^{36}$Ar/$^{38}$Ar values for both samples (3.498 $\pm$ 0.022 for Elmshorn 1 and 3.458 $\pm$ 0.017 for Elmshorn 2) do not match pure cosmogenic compositions

(0.63–0.67; Wieler, 2002); this implies mixing between trapped and cosmogenic Ar, which were separated with a two-component deconvolution between ($^{36}$Ar/$^{38}$Ar)cos and ($^{36}$Ar/$^{38}$Ar)tr. In the absence of solar wind He and Ne, the trapped component used in the deconvolution was constrained between the values for Q and air (5.32–5.34; Busemann et al., 2000; Nier, 1950).

## Production Rates and Cosmic Ray Exposure Ages

In order to calculate the cosmic ray exposure (CRE) age, the production rates of cosmogenic $^{3}$He, $^{21}$Ne, and $^{38}$Ar must first be determined. This was done by using the model for OCs from Leya and Masarik (2009). This model takes into account the preatmospheric size of the meteoroid, the depth of the sample within the meteoroid, and the bulk chemical composition of the sample (see next). Both meteoroid size and sample depth are constrained using the measured purely cosmogenic $^{22}$Ne/$^{21}$Ne ratios as a shielding factor. A single production rate was defined from the two aliquots because their $^{22}$Ne/$^{21}$Ne ratios overlap within error (see next; Noble Gas Composition Section). The error-weighted mean of the two $^{22}$Ne/$^{21}$Ne ratios from Elmshorn 1 and 2 (1.1112 $\pm$ 0.0038) yielded several matches with the model predictions, ranging from radii of 25–500 cm. While the matches were mostly contained within depths of 6–10 cm for the lower radii, they shifted toward the center of the meteoroid at a radius of 120 cm. These deeper positions are statistically highly unlikely to host the sample (Mertens et al., 2021). Given the amount of material found, we also estimate that it would be unrealistic for the meteoroid to have exceeded a radius of 50 cm. For example, given a density of 3.448 g cm$^{-3}$ for fragment E03 (see next; Density Measurements Section) and if only 1% (in this case, the totally found mass of 4277 g) of the preatmospheric material had survived atmospheric entry, the radius of the meteoroid would have been $\sim$30 cm. We consider this 99% ablation thought experiment to be an uncommon case, knowing that the average ablation for OCs with a radius $\le 60$ cm is of 91.5% of the preatmospheric material (Alexeev, 2003). The hypothesis of a relatively small preatmospheric radius along with our derived depths of samples match well with the values measured for $^{26}$Al and $^{60}$Co (see below in Further Short- and Long-Lived Radionuclides by Gamma Spectrometry Section; Alexeev et al., 2001; Kohout et al., 2017), which allows us to set an upper value for the radius at 50 cm. The derived meteoroid size, depth of samples, and production rates are given in Cosmic Ray Exposure Ages Section.

## U/Th-He and K-Ar Gas Retention Ages

The gas retention ages for Elmshorn 1 and 2 were calculated with both U/Th-He and K-Ar chronometers, with the U, Th, and K values measured on the
ICP-SFMS (see Bulk Chemical Characteristics Section). The $ ^{4}\text{He}_{\text{rad}} $ values used in the U/Th-He chronometer were calculated with the safe assumption that the measured $ ^{3}\text{He} $ concentrations were purely cosmogenic and applying a ($ ^{4}\text{He}/^{3}\text{He} $)$_{\text{cos}}$ ratio between 5.2 and 6.1 (Wieler, 2002). The resulting $ ^{4}\text{He}_{\text{cos}} $ concentration was then deducted from our measured $ ^{4}\text{He} $ concentration (considering negligible $ ^{4}\text{He}_{\text{tr}} $). The $ ^{40}\text{Ar}_{\text{rad}} $ values used in the K-Ar chronometer were derived from the deconvoluted $ ^{36}\text{Ar}_{\text{tr}} $ and a ratio ($ ^{40}\text{Ar}/^{36}\text{Ar} $)$_{\text{tr}}$ between 0 and 295.5 (covering both Q and air composition; Busemann et al., 2000; Steiger & Jäger, 1977).

## Radionuclides by Gamma Spectrometry

Cosmogenic as well as primordial radionuclide concentrations were analyzed on the complete pieces of E01 (3731 g) and E02 (233.5 g) by nondestructive gamma spectrometry in the underground laboratory Felsenkeller (Niese et al., 1998) of the VKTA Rossendorf (Dresden).

The laboratory is situated under a rock overburden of 140 m w.e. (water equivalent), resulting in a suppression of the total muon intensity by a factor of 30–40 (Ludwig et al., 2019). Gamma spectrometry systems dedicated to the analysis of low- and very low-activity levels were utilized. Sample E01 was measured on a high-purity germanium (HPGe) detector of 31% relative efficiency. A shielding consisting of 8.5 cm electrolytic copper plus 3.0 cm low-activity and 12.0 cm standard lead was used for the measurements. The spectrometer applied for E02 is based on a coaxial p-type detector of 95% relative efficiency with enhanced front-side sensitivity for low-energy gamma rays. All construction elements were selected for low radioactivity. The passive shielding is graded and consists of 10 cm of electrolytic copper, 10 cm of low-activity lead ($2 \text{ Bq kg}^{-1} \ ^{210}\text{Pb}$), and an outer layer of 10 cm lead with $6 \text{ Bq kg}^{-1} \ ^{210}\text{Pb}$. Up to 2011, the gamma spectrometry system was operated in the UDO laboratory in the Asse salt mine near Braunschweig; it was moved to Dresden in 2014. Detailed information about the gamma spectrometry system can be found in Neumaier et al. (2009). Both gamma spectrometry systems are flushed with vaporized nitrogen to suppress the influence of radon daughter nuclides from the laboratory air.

The nondestructive gamma spectrometric measurement of the E01 mass was carried out in the period August 16 and September 25, 2023 over a total time of 37 days. E02 fragment started on May 4, 2023 (10 days after the bolide event), and continued until June 4, 2023, resulting in a total measurement time of 27 days. Several minor breaks due to device maintenance lasted not longer than 1 day in total. To allow for a more precise radionuclide determination, the energy-dependent detection efficiency of the detector was determined in both cases with the measurement of a meteorite dummy made

of material with known naturally occurring radionuclide contents.

Gamma lines were detected from members of the natural decay series of the primordial nuclides $ ^{238}\text{U} $ and $ ^{232}\text{Th} $, as well as $ ^{40}\text{K} $ and short-lived cosmogenic nuclides. All given specific activities in units of disintegration per minute (dpm) per kg were corrected to April 25, 2023, 14:14, including decay correction during each measuring period itself.

## Magnetic Properties

The magnetic properties of the rock were studied in Aix-en-Provence and in Nördlingen. In Nördlingen, the MS of all available fragments was measured with the handheld device SM-30 from ZH Instruments (www.zhinstruments.cz).

In addition, magnetic measurements on three subsamples from two different specimens (E03 and E07; Table S1) were performed at CEREGE (Aix-en-Provence, France). Hysteresis measurements were performed with a Lake Shore 8604 vibrating sample magnetometer (VSM) with a sensitivity of $ \sim 5 \times 10^{-9} \text{ Am}^2 $. The analysis of hysteresis loops provided the ratio of saturation remanent magnetization ($M_{\text{RS}}$) to saturation magnetization ($M_{\text{S}}$) and the coercive force ($B_{\text{C}}$). The errors concerning the obtained data on Elmshorn fragments are negligible. High-field susceptibility ($\chi_{\text{HF}}$) was determined by a linear fit for applied fields between 1.2 and 1.5 T of the hysteresis loops. Remanent coercive force ($B_{\text{CR}}$) was determined by back field experiments performed with the VSM. The low-field-specific susceptibility ($\chi$ in $\text{m}^3 \text{kg}^{-1}$) was measured using an Agico MFK1 apparatus with sensitivity of $5 \times 10^{-13} \text{ m}^3$, operating at 200 A $\text{m}^{-1}$, and a frequency of 976 Hz. It was measured along three orthogonal axes to take the magnetic anisotropy into account. The coercivity spectrum was estimated up to 1.6 T through stepwise acquisition and measurement of isothermal remanent magnetization (IRM) using the VSM. We determined the $S_{-300}$ ratio, defined as the ratio of the IRM obtained after applying a 3 T field and then a back field of 0.3 T, normalized to the IRM acquired in 3 T.

## Micro-Fourier Transform Infrared Spectroscopy

We used a Bruker Hyperion 3000 attached to a Bruker Vertex 80v located at the IR/IS facility at the Institut für Planetologie (University of Münster) to perform spectral measurements in specular reflectance mode on a thin section of the Elmshorn meteorite with a liquid nitrogen-cooled mercury-cadmium-tellurium detector and a 15× Cassegrain objective. An aperture of $100 \times 100 \text{ µm}^2$ was set for each bulk measurement spot on areas of interests across the macroscopically distinct
ICP-SFMS (see Bulk Chemical Characteristics Section). The $ ^{4}\text{He}_{\text{rad}} $ values used in the U/Th-He chronometer were calculated with the safe assumption that the measured $ ^{3}\text{He} $ concentrations were purely cosmogenic and applying a ($ ^{4}\text{He}/^{3}\text{He} $)$_{\text{cos}}$ ratio between 5.2 and 6.1 (Wieler, 2002). The resulting $ ^{4}\text{He}_{\text{cos}} $ concentration was then deducted from our measured $ ^{4}\text{He} $ concentration (considering negligible $ ^{4}\text{He}_{\text{tr}} $). The $ ^{40}\text{Ar}_{\text{rad}} $ values used in the K-Ar chronometer were derived from the deconvoluted $ ^{36}\text{Ar}_{\text{tr}} $ and a ratio ($ ^{40}\text{Ar}/^{36}\text{Ar} $)$_{\text{tr}}$ between 0 and 295.5 (covering both Q and air composition; Busemann et al., 2000; Steiger & Jäger, 1977).

## Radionuclides by Gamma Spectrometry

Cosmogenic as well as primordial radionuclide concentrations were analyzed on the complete pieces of E01 (3731 g) and E02 (233.5 g) by nondestructive gamma spectrometry in the underground laboratory Felsenkeller (Niese et al., 1998) of the VKTA Rossendorf (Dresden).

The laboratory is situated under a rock overburden of 140 m w.e. (water equivalent), resulting in a suppression of the total muon intensity by a factor of 30–40 (Ludwig et al., 2019). Gamma spectrometry systems dedicated to the analysis of low- and very low-activity levels were utilized. Sample E01 was measured on a high-purity germanium (HPGe) detector of 31% relative efficiency. A shielding consisting of 8.5 cm electrolytic copper plus 3.0 cm low-activity and 12.0 cm standard lead was used for the measurements. The spectrometer applied for E02 is based on a coaxial p-type detector of 95% relative efficiency with enhanced front-side sensitivity for low-energy gamma rays. All construction elements were selected for low radioactivity. The passive shielding is graded and consists of 10 cm of electrolytic copper, 10 cm of low-activity lead ($2 \text{ Bq kg}^{-1} \ ^{210}\text{Pb}$), and an outer layer of 10 cm lead with $6 \text{ Bq kg}^{-1} \ ^{210}\text{Pb}$. Up to 2011, the gamma spectrometry system was operated in the UDO laboratory in the Asse salt mine near Braunschweig; it was moved to Dresden in 2014. Detailed information about the gamma spectrometry system can be found in Neumaier et al. (2009). Both gamma spectrometry systems are flushed with vaporized nitrogen to suppress the influence of radon daughter nuclides from the laboratory air.

The nondestructive gamma spectrometric measurement of the E01 mass was carried out in the period August 16 and September 25, 2023 over a total time of 37 days. E02 fragment started on May 4, 2023 (10 days after the bolide event), and continued until June 4, 2023, resulting in a total measurement time of 27 days. Several minor breaks due to device maintenance lasted not longer than 1 day in total. To allow for a more precise radionuclide determination, the energy-dependent detection efficiency of the detector was determined in both cases with the measurement of a meteorite dummy made

of material with known naturally occurring radionuclide contents.

Gamma lines were detected from members of the natural decay series of the primordial nuclides $ ^{238}\text{U} $ and $ ^{232}\text{Th} $, as well as $ ^{40}\text{K} $ and short-lived cosmogenic nuclides. All given specific activities in units of disintegration per minute (dpm) per kg were corrected to April 25, 2023, 14:14, including decay correction during each measuring period itself.

## Magnetic Properties

The magnetic properties of the rock were studied in Aix-en-Provence and in Nördlingen. In Nördlingen, the MS of all available fragments was measured with the handheld device SM-30 from ZH Instruments (www.zhinstruments.cz).

In addition, magnetic measurements on three subsamples from two different specimens (E03 and E07; Table S1) were performed at CEREGE (Aix-en-Provence, France). Hysteresis measurements were performed with a Lake Shore 8604 vibrating sample magnetometer (VSM) with a sensitivity of $ \sim 5 \times 10^{-9} \text{ Am}^2 $. The analysis of hysteresis loops provided the ratio of saturation remanent magnetization ($M_{\text{RS}}$) to saturation magnetization ($M_{\text{S}}$) and the coercive force ($B_{\text{C}}$). The errors concerning the obtained data on Elmshorn fragments are negligible. High-field susceptibility ($\chi_{\text{HF}}$) was determined by a linear fit for applied fields between 1.2 and 1.5 T of the hysteresis loops. Remanent coercive force ($B_{\text{CR}}$) was determined by back field experiments performed with the VSM. The low-field-specific susceptibility ($\chi$ in $\text{m}^3 \text{kg}^{-1}$) was measured using an Agico MFK1 apparatus with sensitivity of $5 \times 10^{-13} \text{ m}^3$, operating at 200 A $\text{m}^{-1}$, and a frequency of 976 Hz. It was measured along three orthogonal axes to take the magnetic anisotropy into account. The coercivity spectrum was estimated up to 1.6 T through stepwise acquisition and measurement of isothermal remanent magnetization (IRM) using the VSM. We determined the $S_{-300}$ ratio, defined as the ratio of the IRM obtained after applying a 3 T field and then a back field of 0.3 T, normalized to the IRM acquired in 3 T.

## Micro-Fourier Transform Infrared Spectroscopy

We used a Bruker Hyperion 3000 attached to a Bruker Vertex 80v located at the IR/IS facility at the Institut für Planetologie (University of Münster) to perform spectral measurements in specular reflectance mode on a thin section of the Elmshorn meteorite with a liquid nitrogen-cooled mercury-cadmium-tellurium detector and a 15× Cassegrain objective. An aperture of $100 \times 100 \text{ µm}^2$ was set for each bulk measurement spot on areas of interests across the macroscopically distinct
<figure><img src="image_5.png" /></figure>

FIGURE 4. Inspection of the broken surfaces revealed the brecciated texture of the Elmshorn fragment (E03) with (a) large light- and (b) dark-colored fragments embedded in a grayish clastic matrix. (c) A thin section shows various types of fragments in the clastic and dominating (medium light) groundmass, including parts of the dark (upper right) and light (type 6) fragments shown in (a) and (b), respectively. Some other small clasts are highlighted by white dashed lines.

lithologies of Elmshorn fragment E07 (namely, the dark clast; Figure 4b,c, the coarse-grained light clast; Figure 4a,c, and the dominating clastic groundmass; Figure 4c) to obtain a specular reflectance signal. For each lithology, a minimum of 2 × 2 measurement spots was applied in order to map a minimum sample area of 400 × 400 µm². All spectral information was acquired in the energetic range between 2.5 µm (4000 cm⁻¹) and 16.7 µm (600 cm⁻¹) and was averaged, resulting in one spectrum for each lithology. Spectral information obtained from the dark lithology of the meteorite was displayed as a single spot measurement, which was compared—based on the dark optical appearance—to the dark lithology of the Chelyabinsk meteorite. The

microscope was purged with dry air during measurements, as was the sample compartment, in order to avoid additional atmospheric interferences. All measurements were integrated over 512 scans to improve the signal-to-noise ratio, and the bulk measurements were smoothed with a Savitzky-Golay filter (10 pt). A suitable (i.e., a comparably flat) gold standard was used for calibration, and the spectral resolution was set to 2 cm⁻¹. All spectral data from the Elmshorn samples will be available with the sample ID 609 Elmshorn PL23029 in the Infrared and Raman for Interplanetary Spectroscopy (IRIS) database for space science missions (Weber et al., 2018). Spectral data that were used for comparison, for example, albite and Chelyabinsk dark
<figure><img src="image_6.png" /></figure>

FIGURE 4. Inspection of the broken surfaces revealed the brecciated texture of the Elmshorn fragment (E03) with (a) large light- and (b) dark-colored fragments embedded in a grayish clastic matrix. (c) A thin section shows various types of fragments in the clastic and dominating (medium light) groundmass, including parts of the dark (upper right) and light (type 6) fragments shown in (a) and (b), respectively. Some other small clasts are highlighted by white dashed lines.

lithologies of Elmshorn fragment E07 (namely, the dark clast; Figure 4b,c, the coarse-grained light clast; Figure 4a,c, and the dominating clastic groundmass; Figure 4c) to obtain a specular reflectance signal. For each lithology, a minimum of 2 × 2 measurement spots was applied in order to map a minimum sample area of 400 × 400 µm². All spectral information was acquired in the energetic range between 2.5 µm (4000 cm⁻¹) and 16.7 µm (600 cm⁻¹) and was averaged, resulting in one spectrum for each lithology. Spectral information obtained from the dark lithology of the meteorite was displayed as a single spot measurement, which was compared—based on the dark optical appearance—to the dark lithology of the Chelyabinsk meteorite. The

microscope was purged with dry air during measurements, as was the sample compartment, in order to avoid additional atmospheric interferences. All measurements were integrated over 512 scans to improve the signal-to-noise ratio, and the bulk measurements were smoothed with a Savitzky-Golay filter (10 pt). A suitable (i.e., a comparably flat) gold standard was used for calibration, and the spectral resolution was set to 2 cm⁻¹. All spectral data from the Elmshorn samples will be available with the sample ID 609 Elmshorn PL23029 in the Infrared and Raman for Interplanetary Spectroscopy (IRIS) database for space science missions (Weber et al., 2018). Spectral data that were used for comparison, for example, albite and Chelyabinsk dark
chip, ID 126 and ID 96, respectively, are already implemented and available in the IRIS database. The spectral data are available on the IRIS database at http://bc-mertis-pi.uni-muenster.de/ and searchable either by ID number or name.

## Density

The density of the Elmshorn meteorite was measured by two different methods: In one approach, the bulk density of the rough piece (E02) of $233.5 \pm 0.1$ g was determined in Augsburg with the method described by Consolmagno et al. (2008) using 40 µm diameter glass beads. In another approach, the volumes of the same piece and of a different fragment (51.62 g from E03) were derived from X-ray computed tomography (CT) 3-D images and used for density calculations. Consistent results were obtained for the 233.5 g piece by both methods. For the largest fragment of Elmshorn (E01), the volume was obtained by digital optical techniques at the Digimold Reverse Engineering Company in Sonneberg (Germany).

## CT and Scanning

CT was performed three times: At the Helmholtz Institute Freiberg for Resource Technology, at the RIF e.V. (Dortmund), and at the private company 3D-MT in Augsburg (all in Germany).

In Freiberg, the Elmshorn meteorite sample (E02) of 233.5 g was scanned in a CoreTom CT scanner from Tescan. Two scans were performed, namely high-resolution region of interest (used in image S1) and low resolution (used to calculate the sample volume). The high-resolution image with a 20-µm voxel size was obtained using an X-ray energy of 180 keV with a power of 20 W and one 0.5-mm thick copper filter mounted at the source. The low-resolution image with a 56-µm voxel size was obtained using an X-ray energy of 180 keV with a power of 56 W and one 2-mm thick steel filter mounted at the source. The current used was optimized so that the resolution was limited by geometrical factors and not by the spot size of the beam. Reconstruction was done using the XRE recon v1.0.0.111. A beam-hardening correction of 0.12 was used to homogenize the gray scale throughout the samples. Image processing and visualization were done in Avizo 9.3.0. A 3-D nonlocal-means filter (window = 10, neighbor = 3, similarity = 0.7) was used in Figure S1 to remove noise with minimum impact on object boundaries.

In Dortmund, the interior of a piece of the 51.62 g Elmshorn fragment E03 was examined using a CT system manufactured by GE Sensing & Inspection (phoenix1x-ray vltomelx 1 240D). The X-ray energy was 120 keV with a power of 12 W. Subsequent reconstruction was performed with filters to suppress artifacts and beam hardening using DATOS X-Reconstruction software (GE Sensing &

Inspection). The voxel size was ~25.6 µm, and subsequent visualization and analysis were performed using Dragonfly software from Comet Technologies Canada, Inc.

At 3D-MT in Augsburg (Germany), the smallest of the 21 recovered samples (E21), at 1.09 g, was scanned using a GE phoenix vltomelx m CT scanner with excellent resolution (voxel size 6.9165 µm).

## Find Locations

The stony meteorites were found at 21 different locations in the northern part of the city of Elmshorn (Figure 2). The three largest samples were found by the owners of their houses, while most of the smaller samples were found in inhabited terrain after an intensive effort by private searches. Two railway tracks intersect the strewn field; most of the small pieces were found northeast of the tracks. The typical landscape north of the tracks and within the inhabited terrain are shown in Figure 3.

# RESULTS

## Hand Specimen Characteristics

Currently, 21 pieces have been recovered in a strewn field of about $2.5 \times 1.5$ km² within a few weeks, totaling a mass of 4.282 kg (Figure 2; Table S1). Depending on the impact location, some fragments were perfectly preserved with a complete fusion crust (Figure 1), whereas others were smashed into many pieces. Upon inspection of the broken surfaces, the brecciated texture of Elmshorn was found to be perfectly presented (Figure 4). Within a dominating grayish groundmass, large light- and dark-colored fragments are easily recognized (Figure 4a,b). Thus, obviously, Elmshorn is a breccia consisting of a mixture of different lithologies. This textural characteristic is also observable in polished thin sections (Figure 4c).

## CT Observations

Some typical images from the interiors of the Elmshorn samples E02, E03, and E21 are presented in Figures S1–S3. The brecciated texture of Elmshorn is also visible during CT studies (Figures S1d and S2d). The metals and sulfides in Elmshorn are also found to be heterogeneously distributed (e.g., Figure S1b). In all studied pieces, millimeter-sized, elongated metal grains can be found (Figures S1–S3), as can remarkable metal-silicate intergrowths, which are probably related to shock-darkened fragments (Figure S2d). In such a case, metals and sulfides fill the cleavage planes, fractures, boundaries, and voids of the main silicates (mainly olivine and low-Ca pyroxene; compare Morlok et al., 2017).
chip, ID 126 and ID 96, respectively, are already implemented and available in the IRIS database. The spectral data are available on the IRIS database at http://bc-mertis-pi.uni-muenster.de/ and searchable either by ID number or name.

## Density

The density of the Elmshorn meteorite was measured by two different methods: In one approach, the bulk density of the rough piece (E02) of $233.5 \pm 0.1$ g was determined in Augsburg with the method described by Consolmagno et al. (2008) using 40 µm diameter glass beads. In another approach, the volumes of the same piece and of a different fragment (51.62 g from E03) were derived from X-ray computed tomography (CT) 3-D images and used for density calculations. Consistent results were obtained for the 233.5 g piece by both methods. For the largest fragment of Elmshorn (E01), the volume was obtained by digital optical techniques at the Digimold Reverse Engineering Company in Sonneberg (Germany).

## CT and Scanning

CT was performed three times: At the Helmholtz Institute Freiberg for Resource Technology, at the RIF e.V. (Dortmund), and at the private company 3D-MT in Augsburg (all in Germany).

In Freiberg, the Elmshorn meteorite sample (E02) of 233.5 g was scanned in a CoreTom CT scanner from Tescan. Two scans were performed, namely high-resolution region of interest (used in image S1) and low resolution (used to calculate the sample volume). The high-resolution image with a 20-µm voxel size was obtained using an X-ray energy of 180 keV with a power of 20 W and one 0.5-mm thick copper filter mounted at the source. The low-resolution image with a 56-µm voxel size was obtained using an X-ray energy of 180 keV with a power of 56 W and one 2-mm thick steel filter mounted at the source. The current used was optimized so that the resolution was limited by geometrical factors and not by the spot size of the beam. Reconstruction was done using the XRE recon v1.0.0.111. A beam-hardening correction of 0.12 was used to homogenize the gray scale throughout the samples. Image processing and visualization were done in Avizo 9.3.0. A 3-D nonlocal-means filter (window = 10, neighbor = 3, similarity = 0.7) was used in Figure S1 to remove noise with minimum impact on object boundaries.

In Dortmund, the interior of a piece of the 51.62 g Elmshorn fragment E03 was examined using a CT system manufactured by GE Sensing & Inspection (phoenix1x-ray vltomelx 1 240D). The X-ray energy was 120 keV with a power of 12 W. Subsequent reconstruction was performed with filters to suppress artifacts and beam hardening using DATOS X-Reconstruction software (GE Sensing &

Inspection). The voxel size was ~25.6 µm, and subsequent visualization and analysis were performed using Dragonfly software from Comet Technologies Canada, Inc.

At 3D-MT in Augsburg (Germany), the smallest of the 21 recovered samples (E21), at 1.09 g, was scanned using a GE phoenix vltomelx m CT scanner with excellent resolution (voxel size 6.9165 µm).

## Find Locations

The stony meteorites were found at 21 different locations in the northern part of the city of Elmshorn (Figure 2). The three largest samples were found by the owners of their houses, while most of the smaller samples were found in inhabited terrain after an intensive effort by private searches. Two railway tracks intersect the strewn field; most of the small pieces were found northeast of the tracks. The typical landscape north of the tracks and within the inhabited terrain are shown in Figure 3.

# RESULTS

## Hand Specimen Characteristics

Currently, 21 pieces have been recovered in a strewn field of about $2.5 \times 1.5$ km² within a few weeks, totaling a mass of 4.282 kg (Figure 2; Table S1). Depending on the impact location, some fragments were perfectly preserved with a complete fusion crust (Figure 1), whereas others were smashed into many pieces. Upon inspection of the broken surfaces, the brecciated texture of Elmshorn was found to be perfectly presented (Figure 4). Within a dominating grayish groundmass, large light- and dark-colored fragments are easily recognized (Figure 4a,b). Thus, obviously, Elmshorn is a breccia consisting of a mixture of different lithologies. This textural characteristic is also observable in polished thin sections (Figure 4c).

## CT Observations

Some typical images from the interiors of the Elmshorn samples E02, E03, and E21 are presented in Figures S1–S3. The brecciated texture of Elmshorn is also visible during CT studies (Figures S1d and S2d). The metals and sulfides in Elmshorn are also found to be heterogeneously distributed (e.g., Figure S1b). In all studied pieces, millimeter-sized, elongated metal grains can be found (Figures S1–S3), as can remarkable metal-silicate intergrowths, which are probably related to shock-darkened fragments (Figure S2d). In such a case, metals and sulfides fill the cleavage planes, fractures, boundaries, and voids of the main silicates (mainly olivine and low-Ca pyroxene; compare Morlok et al., 2017).
## Mineralogy

The thin sections prepared from the broken fragment (E03; Figure 4c) show that the rock is a complex breccia consisting of equilibrated and recrystallized lithologies (types 4–6) as well as unequilibrated type 3 lithologies (Table 1; Figure 4). The boundaries of several large fragments are well defined (Figure 4); however, those of smaller fragments in the groundmass are difficult to detect. Overall, different types of chondrules are well preserved (Figure 6). Barred olivine (BO), radial pyroxene, and cryptocrystalline (C) chondrules are easily recognized, whereas porphyritic chondrules are less easy to detect but are present in several types 3 and 4 lithic clasts. In clasts of higher petrologic grade (types 5 and 6), they easily merge with the matrix due to metamorphic recrystallization. Some Al-rich chondrules are present (e.g., Bischoff & Keil, 1983a, 1983b, 1984; Ebert & Bischoff, 2016a). The example shown in Figure 6c,d is rich in Na₂O and K₂O and mainly consists of a Na,K,Al-rich mesostasis embedding zoned olivine (Fa<sub>1–27</sub>) and skeletal Al-Ti diopside (fassaite; Figure 6c,d; Table 2). On average, the mesostasis contains about 10.5 wt% Na₂O, 5 wt% K₂O, and 23 wt% Al₂O₃ (Table 2). Olivine is by far the most abundant phase and heterogeneous in composition throughout all polished sections. The mean composition of 103 randomly and automatically analyzed olivines (grid analysis) was found to be Fa<sub>19.6±1.5</sub> with a compositional range between 14 and 24 mole% Fa (Table 1). However, a detailed search of individual olivines revealed a range between Fa<sub>1</sub> and Fa<sub>32</sub>. The random analysis of olivine shows that most grains plot at Fa<sub>19–20</sub>, but a significant number of olivines have Fa contents above 20 mole% (Figure 8). The 78 randomly analyzed low-Ca pyroxenes have compositions of Fs<sub>16.1±2.4</sub>Wo<sub>1.6±1.4</sub> (Table 1) and the Fs contents vary between 9 and 24 mole%. Plagioclase analyses were mainly obtained from the large H6 fragment (compare Figure 4), revealing a mean composition of An<sub>11.3</sub>Ab<sub>86.6</sub>Or<sub>2.1</sub> (Table 1). Based on their size, chromites and phosphates were also easily found and analyzed in the metamorphosed clasts. The apatites were found to be rich in Cl (5.5–6.2 wt%) and similar in composition to those reported from Ward et al. (2017) for many other OCs. However, they are different from apatites found in the recently analyzed Renchen L OC breccia, which have 3.4 wt% F (Bischoff, Barrat, et al., 2019). The merrillites have, on average, 2.9 wt% Na₂O and 3.6 wt% MgO (Table 2). Chromites are relatively homogeneous in composition, with 57.1 ± 0.40 wt% Cr₂O₃ and 29.3 ± 0.47 wt% FeO (Table 2). Metals and sulfides are abundant throughout all the thin sections, and their mean compositions are given in Table 3. Kamacite is certainly more abundant than taenite. The Ni and Co concentrations of kamacite vary (2.0–8.0 wt% and 0.64–

0.80 wt%, respectively). Frequently, kamacites were found to have relatively low Ni concentrations of about 2–4 wt %. The taenite composition was found to vary, with Ni content varying between 17 and 39 wt% (mean: 29.2 wt%) and Co concentrations between 0.13 and 0.67 wt% (mean: 0.35 wt%); however, we cannot rule out that this observation reflects the analyses of fine-grained intergrowths of taenite and kamacite. Some grains of tetrataenite (~Fe₅₀Ni₅₀) were also detected. The sulfide is pure troilite with 35.9 wt% S and 61.7 wt% Fe (Table 3).

For comparison, olivine and low-Ca pyroxene within a second sample (E07) of the strewn field were analyzed (grid analysis). Within this sample, the mean composition of 106 randomly analyzed olivines was found to be Fa<sub>20.7±2.3</sub> with a compositional range between 10 and 32 mole% Fa (Table 1; Figure 8). The coexisting low-Ca pyroxene was found to have a mean composition of Fs<sub>16.2±2.8</sub>En<sub>83.0±3.0</sub>Wo<sub>0.8±0.6</sub> (n = 79) with a range between 5 and 24 mole% Fs.

When viewed in detail, the mineralogy of Elmshorn is more complex than indicated by the randomly obtained data on the mineral chemistry. Within the studied thin sections, most obvious lithologies are a light, strongly recrystallized (type 6) fragment (Figure 4) and a fine-grained dark clast (Figures 4 and 7). Olivine (Fa<sub>19.6±0.32</sub>; n = 18) and low-Ca pyroxene compositions (Fs<sub>15.5±0.5</sub>Wo<sub>1.4±0.2</sub>) of the light clast clearly plot into the field for H chondrites (Figure 8). Plagioclase grains in the clast reach sizes of up to about 100 µm. Some large chromites, apatites, and troilites also occur (Tables 1–3). The kamacite grains contain 5.8 wt% Ni and 0.71 wt% Co, on average (Table 3). The Co concentrations are somewhat higher than those given by Rubin (1990; ~0.5 wt%).

The dark clast has abundant fine-grained material embedding a low abundance of chondrules and chondrule fragments. The textural characteristics (Figure 7b) resemble those of impact melts, but distinct differences exist. The most significant difference is the skeletal shape of the metals (Figure 7b), which are spherulitic in typical impact melt rocks. Within the dark clast, the small metal grains in the fine-grained groundmass are homogeneously distributed and skeletal in shape. Their occurrence is probably responsible for the dark appearance of the clast in transmitted light (Figures 4 and 7). The compositions of olivine (Fa<sub>20.2±0.4</sub>; n = 18; Table 1; Figure 8) are rather constant and the low-Ca pyroxenes (Fs<sub>15.9±1.8</sub>Wo<sub>0.8±0.3</sub>) vary moderately, as is often observed in H4 chondrites since the equilibration of olivine is faster than that of low-Ca pyroxene. The composition of the matrix olivine is ~Fa<sub>20.5</sub>.

A 2-mm-sized, large clast of an unusual melt is an eye-catching component in one of the thin sections (Figure 5f). The silicate-rich object contains skeletal
## Mineralogy

The thin sections prepared from the broken fragment (E03; Figure 4c) show that the rock is a complex breccia consisting of equilibrated and recrystallized lithologies (types 4–6) as well as unequilibrated type 3 lithologies (Table 1; Figure 4). The boundaries of several large fragments are well defined (Figure 4); however, those of smaller fragments in the groundmass are difficult to detect. Overall, different types of chondrules are well preserved (Figure 6). Barred olivine (BO), radial pyroxene, and cryptocrystalline (C) chondrules are easily recognized, whereas porphyritic chondrules are less easy to detect but are present in several types 3 and 4 lithic clasts. In clasts of higher petrologic grade (types 5 and 6), they easily merge with the matrix due to metamorphic recrystallization. Some Al-rich chondrules are present (e.g., Bischoff & Keil, 1983a, 1983b, 1984; Ebert & Bischoff, 2016a). The example shown in Figure 6c,d is rich in Na₂O and K₂O and mainly consists of a Na,K,Al-rich mesostasis embedding zoned olivine (Fa<sub>1–27</sub>) and skeletal Al-Ti diopside (fassaite; Figure 6c,d; Table 2). On average, the mesostasis contains about 10.5 wt% Na₂O, 5 wt% K₂O, and 23 wt% Al₂O₃ (Table 2). Olivine is by far the most abundant phase and heterogeneous in composition throughout all polished sections. The mean composition of 103 randomly and automatically analyzed olivines (grid analysis) was found to be Fa<sub>19.6±1.5</sub> with a compositional range between 14 and 24 mole% Fa (Table 1). However, a detailed search of individual olivines revealed a range between Fa<sub>1</sub> and Fa<sub>32</sub>. The random analysis of olivine shows that most grains plot at Fa<sub>19–20</sub>, but a significant number of olivines have Fa contents above 20 mole% (Figure 8). The 78 randomly analyzed low-Ca pyroxenes have compositions of Fs<sub>16.1±2.4</sub>Wo<sub>1.6±1.4</sub> (Table 1) and the Fs contents vary between 9 and 24 mole%. Plagioclase analyses were mainly obtained from the large H6 fragment (compare Figure 4), revealing a mean composition of An<sub>11.3</sub>Ab<sub>86.6</sub>Or<sub>2.1</sub> (Table 1). Based on their size, chromites and phosphates were also easily found and analyzed in the metamorphosed clasts. The apatites were found to be rich in Cl (5.5–6.2 wt%) and similar in composition to those reported from Ward et al. (2017) for many other OCs. However, they are different from apatites found in the recently analyzed Renchen L OC breccia, which have 3.4 wt% F (Bischoff, Barrat, et al., 2019). The merrillites have, on average, 2.9 wt% Na₂O and 3.6 wt% MgO (Table 2). Chromites are relatively homogeneous in composition, with 57.1 ± 0.40 wt% Cr₂O₃ and 29.3 ± 0.47 wt% FeO (Table 2). Metals and sulfides are abundant throughout all the thin sections, and their mean compositions are given in Table 3. Kamacite is certainly more abundant than taenite. The Ni and Co concentrations of kamacite vary (2.0–8.0 wt% and 0.64–

0.80 wt%, respectively). Frequently, kamacites were found to have relatively low Ni concentrations of about 2–4 wt %. The taenite composition was found to vary, with Ni content varying between 17 and 39 wt% (mean: 29.2 wt%) and Co concentrations between 0.13 and 0.67 wt% (mean: 0.35 wt%); however, we cannot rule out that this observation reflects the analyses of fine-grained intergrowths of taenite and kamacite. Some grains of tetrataenite (~Fe₅₀Ni₅₀) were also detected. The sulfide is pure troilite with 35.9 wt% S and 61.7 wt% Fe (Table 3).

For comparison, olivine and low-Ca pyroxene within a second sample (E07) of the strewn field were analyzed (grid analysis). Within this sample, the mean composition of 106 randomly analyzed olivines was found to be Fa<sub>20.7±2.3</sub> with a compositional range between 10 and 32 mole% Fa (Table 1; Figure 8). The coexisting low-Ca pyroxene was found to have a mean composition of Fs<sub>16.2±2.8</sub>En<sub>83.0±3.0</sub>Wo<sub>0.8±0.6</sub> (n = 79) with a range between 5 and 24 mole% Fs.

When viewed in detail, the mineralogy of Elmshorn is more complex than indicated by the randomly obtained data on the mineral chemistry. Within the studied thin sections, most obvious lithologies are a light, strongly recrystallized (type 6) fragment (Figure 4) and a fine-grained dark clast (Figures 4 and 7). Olivine (Fa<sub>19.6±0.32</sub>; n = 18) and low-Ca pyroxene compositions (Fs<sub>15.5±0.5</sub>Wo<sub>1.4±0.2</sub>) of the light clast clearly plot into the field for H chondrites (Figure 8). Plagioclase grains in the clast reach sizes of up to about 100 µm. Some large chromites, apatites, and troilites also occur (Tables 1–3). The kamacite grains contain 5.8 wt% Ni and 0.71 wt% Co, on average (Table 3). The Co concentrations are somewhat higher than those given by Rubin (1990; ~0.5 wt%).

The dark clast has abundant fine-grained material embedding a low abundance of chondrules and chondrule fragments. The textural characteristics (Figure 7b) resemble those of impact melts, but distinct differences exist. The most significant difference is the skeletal shape of the metals (Figure 7b), which are spherulitic in typical impact melt rocks. Within the dark clast, the small metal grains in the fine-grained groundmass are homogeneously distributed and skeletal in shape. Their occurrence is probably responsible for the dark appearance of the clast in transmitted light (Figures 4 and 7). The compositions of olivine (Fa<sub>20.2±0.4</sub>; n = 18; Table 1; Figure 8) are rather constant and the low-Ca pyroxenes (Fs<sub>15.9±1.8</sub>Wo<sub>0.8±0.3</sub>) vary moderately, as is often observed in H4 chondrites since the equilibration of olivine is faster than that of low-Ca pyroxene. The composition of the matrix olivine is ~Fa<sub>20.5</sub>.

A 2-mm-sized, large clast of an unusual melt is an eye-catching component in one of the thin sections (Figure 5f). The silicate-rich object contains skeletal
<table><caption>TABLE 1. Mean chemical composition of the main silicates in the Elmshorn bulk rock E03 (bulk-1) and of olivine from some of its fragments (exception: olivine-bulk-2 is from fragment E07).</caption><thead><tr><th></th><th>Olivine<br>(bulk-1)<br>(n = 103)</th><th>Low-Ca Px<br>(bulk-1)<br>(n = 78)</th><th>Plagioclase<sup>a</sup><br>(bulk-1)<br>(n = 16)</th><th>Olivine<br>(bulk-2)<br>(n = 106)</th><th>H6 clast<br>olivine<br>(n = 18)</th><th>Dark clast<br>(H) olivine<br>(n = 18)</th><th>H/L3.9 clast<br>Frag H<br>(n = 16)</th><th>H/L4 clast<br>Frag G<br>(n = 15)</th><th>H/L3.9 clast<br>Frag A<br>(n = 17)</th><th>H/L3.9 clast<br>Frag B<br>(n = 19)</th><th>H/L4 clast<br>Frag F<br>(n = 17)</th></tr></thead><tbody><tr><td>SiO<sub>2</sub></td><td>39.0 ± 0.6</td><td>56.1 ± 1.0</td><td>65.5 ± 0.8</td><td>39.0 ± 0.7</td><td>38.8 ± 0.2</td><td>38.7 ± 0.4</td><td>38.8 ± 0.2</td><td>38.3 ± 0.4</td><td>38.5 ± 0.3</td><td>38.5 ± 0.3</td><td>38.5 ± 0.2</td></tr><tr><td>Al<sub>2</sub>O<sub>3</sub></td><td>&lt;0.02</td><td>0.43</td><td>20.3 ± 0.5</td><td>&lt;0.02</td><td>&lt;0.01</td><td>&lt;0.01</td><td>n.d.</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.01</td><td>&lt;0.01</td></tr><tr><td>Cr<sub>2</sub>O<sub>3</sub></td><td>0.05</td><td>0.29</td><td>&lt;0.03</td><td>0.04</td><td>0.03</td><td>0.04</td><td>&lt;0.04</td><td>&lt;0.03</td><td>&lt;0.03</td><td>&lt;0.02</td><td>0.05</td></tr><tr><td>FeO</td><td>18.2 ± 1.3</td><td>10.7 ± 1.5</td><td>0.53 ± 0.2</td><td>19.4 ± 2.0</td><td>18.4 ± 0.3</td><td>18.9 ± 0.4</td><td>19.5 ± 1.0</td><td>19.9 ± 1.0</td><td>20.4 ± 1.1</td><td>19.9 ± 1.2</td><td>19.4 ± 0.6</td></tr><tr><td>MnO</td><td>0.44 ± 0.05</td><td>0.47 ± 0.11</td><td>&lt;0.01</td><td>0.47 ± 0.05</td><td>0.46 ± 0.04</td><td>0.46 ± 0.3</td><td>0.39 ± 0.07</td><td>0.45 ± 0.05</td><td>0.44 ± 0.04</td><td>0.48 ± 0.04</td><td>0.45 ± 0.04</td></tr><tr><td>MgO</td><td>41.6 ± 1.2</td><td>30.7 ± 1.7</td><td>0.19</td><td>41.5 ± 1.8</td><td>42.1 ± 0.5</td><td>41.7 ± 0.4</td><td>41.0 ± 0.9</td><td>40.5 ± 0.9</td><td>40.1 ± 0.9</td><td>40.6 ± 1.0</td><td>40.9 ± 0.5</td></tr><tr><td>CaO</td><td>0.03</td><td>0.80 ± 0.70</td><td>2.41 ± 0.4</td><td>0.03</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.03</td><td>&lt;0.01</td><td>&lt;0.02</td></tr><tr><td>Na<sub>2</sub>O</td><td>&lt;0.01</td><td>0.08</td><td>10.2 ± 0.4</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td></tr><tr><td>K<sub>2</sub>O</td><td>&lt;0.01</td><td>&lt;0.01</td><td>0.37 ± 0.2</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td></tr><tr><td>P<sub>2</sub>O<sub>5</sub></td><td>&lt;0.03</td><td>&lt;0.01</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.04</td><td>0.05</td><td>n.a.</td><td>n.a.</td><td>n.a.</td></tr><tr><td>Total</td><td>99.39</td><td>99.59</td><td>99.56</td><td>100.50</td><td>99.86</td><td>99.88</td><td>99.83</td><td>99.30</td><td>99.54</td><td>99.54</td><td>99.35</td></tr><tr><td>Fe</td><td>19.6 ± 1.5</td><td></td><td></td><td>20.7 ± 2.3</td><td>19.6 ± 0.3</td><td>20.2 ± 0.4</td><td>21.0 ± 1.2</td><td>21.5 ± 1.0</td><td>22.0 ± 1.3</td><td>21.5 ± 1.4</td><td>20.9 ± 0.7</td></tr><tr><td>Te</td><td>0.49 ± 0.06</td><td></td><td></td><td>0.52 ± 0.05</td><td>0.50 ± 0.04</td><td>0.50 ± 0.03</td><td>0.43 ± 0.07</td><td>0.50 ± 0.05</td><td>0.49 ± 0.04</td><td>0.52 ± 0.04</td><td>0.49 ± 0.04</td></tr><tr><td>Fs</td><td></td><td>16.1 ± 2.4</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Wo</td><td></td><td>1.6 ± 1.4</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>An</td><td></td><td></td><td>11.3 ± 2.2</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Or</td><td></td><td></td><td>2.1 ± 0.8</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

Note: All data in wt%.

Abbreviations: n, number of analyses; n.a., not analyzed; n.d., not detected; Plag, plagioclase; Px, pyroxene; Te, tephroite (Mn) component in olivine.

a Mostly plagioclase from the H6 clast.
<table><caption>TABLE 1. Mean chemical composition of the main silicates in the Elmshorn bulk rock E03 (bulk-1) and of olivine from some of its fragments (exception: olivine-bulk-2 is from fragment E07).</caption><thead><tr><th></th><th>Olivine<br>(bulk-1)<br>(n = 103)</th><th>Low-Ca Px<br>(bulk-1)<br>(n = 78)</th><th>Plagioclase<sup>a</sup><br>(bulk-1)<br>(n = 16)</th><th>Olivine<br>(bulk-2)<br>(n = 106)</th><th>H6 clast<br>olivine<br>(n = 18)</th><th>Dark clast<br>(H) olivine<br>(n = 18)</th><th>H/L3.9 clast<br>Frag H<br>(n = 16)</th><th>H/L4 clast<br>Frag G<br>(n = 15)</th><th>H/L3.9 clast<br>Frag A<br>(n = 17)</th><th>H/L3.9 clast<br>Frag B<br>(n = 19)</th><th>H/L4 clast<br>Frag F<br>(n = 17)</th></tr></thead><tbody><tr><td>SiO<sub>2</sub></td><td>39.0 ± 0.6</td><td>56.1 ± 1.0</td><td>65.5 ± 0.8</td><td>39.0 ± 0.7</td><td>38.8 ± 0.2</td><td>38.7 ± 0.4</td><td>38.8 ± 0.2</td><td>38.3 ± 0.4</td><td>38.5 ± 0.3</td><td>38.5 ± 0.3</td><td>38.5 ± 0.2</td></tr><tr><td>Al<sub>2</sub>O<sub>3</sub></td><td>&lt;0.02</td><td>0.43</td><td>20.3 ± 0.5</td><td>&lt;0.02</td><td>&lt;0.01</td><td>&lt;0.01</td><td>n.d.</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.01</td><td>&lt;0.01</td></tr><tr><td>Cr<sub>2</sub>O<sub>3</sub></td><td>0.05</td><td>0.29</td><td>&lt;0.03</td><td>0.04</td><td>0.03</td><td>0.04</td><td>&lt;0.04</td><td>&lt;0.03</td><td>&lt;0.03</td><td>&lt;0.02</td><td>0.05</td></tr><tr><td>FeO</td><td>18.2 ± 1.3</td><td>10.7 ± 1.5</td><td>0.53 ± 0.2</td><td>19.4 ± 2.0</td><td>18.4 ± 0.3</td><td>18.9 ± 0.4</td><td>19.5 ± 1.0</td><td>19.9 ± 1.0</td><td>20.4 ± 1.1</td><td>19.9 ± 1.2</td><td>19.4 ± 0.6</td></tr><tr><td>MnO</td><td>0.44 ± 0.05</td><td>0.47 ± 0.11</td><td>&lt;0.01</td><td>0.47 ± 0.05</td><td>0.46 ± 0.04</td><td>0.46 ± 0.3</td><td>0.39 ± 0.07</td><td>0.45 ± 0.05</td><td>0.44 ± 0.04</td><td>0.48 ± 0.04</td><td>0.45 ± 0.04</td></tr><tr><td>MgO</td><td>41.6 ± 1.2</td><td>30.7 ± 1.7</td><td>0.19</td><td>41.5 ± 1.8</td><td>42.1 ± 0.5</td><td>41.7 ± 0.4</td><td>41.0 ± 0.9</td><td>40.5 ± 0.9</td><td>40.1 ± 0.9</td><td>40.6 ± 1.0</td><td>40.9 ± 0.5</td></tr><tr><td>CaO</td><td>0.03</td><td>0.80 ± 0.70</td><td>2.41 ± 0.4</td><td>0.03</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.03</td><td>&lt;0.01</td><td>&lt;0.02</td></tr><tr><td>Na<sub>2</sub>O</td><td>&lt;0.01</td><td>0.08</td><td>10.2 ± 0.4</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td></tr><tr><td>K<sub>2</sub>O</td><td>&lt;0.01</td><td>&lt;0.01</td><td>0.37 ± 0.2</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td><td>&lt;0.01</td></tr><tr><td>P<sub>2</sub>O<sub>5</sub></td><td>&lt;0.03</td><td>&lt;0.01</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.02</td><td>&lt;0.04</td><td>0.05</td><td>n.a.</td><td>n.a.</td><td>n.a.</td></tr><tr><td>Total</td><td>99.39</td><td>99.59</td><td>99.56</td><td>100.50</td><td>99.86</td><td>99.88</td><td>99.83</td><td>99.30</td><td>99.54</td><td>99.54</td><td>99.35</td></tr><tr><td>Fa</td><td>19.6 ± 1.5</td><td></td><td></td><td>20.7 ± 2.3</td><td>19.6 ± 0.3</td><td>20.2 ± 0.4</td><td>21.0 ± 1.2</td><td>21.5 ± 1.0</td><td>22.0 ± 1.3</td><td>21.5 ± 1.4</td><td>20.9 ± 0.7</td></tr><tr><td>Te</td><td>0.49 ± 0.06</td><td></td><td></td><td>0.52 ± 0.05</td><td>0.50 ± 0.04</td><td>0.50 ± 0.03</td><td>0.43 ± 0.07</td><td>0.50 ± 0.05</td><td>0.49 ± 0.04</td><td>0.52 ± 0.04</td><td>0.49 ± 0.04</td></tr><tr><td>Fs</td><td></td><td>16.1 ± 2.4</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Wo</td><td></td><td>1.6 ± 1.4</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>An</td><td></td><td></td><td>11.3 ± 2.2</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Or</td><td></td><td></td><td>2.1 ± 0.8</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>

Note: All data in wt%.

Abbreviations: n, number of analyses; n.a., not analyzed; n.d., not detected; Plag, plagioclase; Px, pyroxene; Te, tephroite (Mn) component in olivine.

a Mostly plagioclase from the H6 clast.
<table><caption>TABLE 2. Chemical composition of minor phases in the Elmshorn breccia E03 as well as the bulk composition and (contaminated) phases of the melt fragment M from E03 (Figure 5f and Figure S1). Mesostasis and fassaite from the Na,Al-rich chondrule shown in Figure 6c,d.</caption><thead><tr><th rowspan="2"></th><th rowspan="2">Mesostasis<br>(bulk) (n = 5)</th><th rowspan="2">Fassaite<br>(mean)<br>(n = 2)</th><th rowspan="2">Apatite<br>(n = 5)<sup>a</sup></th><th rowspan="2">Merrillite<br>(n = 6)</th><th rowspan="2">Chromite<br>(n = 8)</th><th colspan="4">Melt fragment M</th></tr><tr><th>Bulk chem<br>(n = 397)</th><th>Olivine<br>(n = 20)</th><th>Low-Ca<br>pyroxene<br>(n = 16)</th><th>Ca<br>pyroxene<br>(n = 6)</th></tr></thead><tbody><tr><td>SiO<sub>2</sub></td><td>57.5 ± 2.8</td><td>52.7</td><td>0.14</td><td>0.09</td><td>0.23 ± 0.15</td><td>45.0</td><td>39.0 ± 0.4</td><td>54.1 ± 0.9</td><td>49.3 ± 0.7</td></tr><tr><td>TiO<sub>2</sub></td><td>0.90 ± 0.08</td><td>0.93</td><td>&lt;0.03</td><td>&lt;0.01</td><td>2.33 ± 0.27</td><td>0.27</td><td>0.12</td><td>0.38</td><td>0.72</td></tr><tr><td>Al<sub>2</sub>O<sub>3</sub></td><td>23.0 ± 1.4</td><td>21.9</td><td>&lt;0.04</td><td>&lt;0.01</td><td>6.1 ± 0.64</td><td>6.4</td><td>1.03 ± 0.34</td><td>12.0 ± 0.6</td><td>6.2 ± 0.9</td></tr><tr><td>Cr<sub>2</sub>O<sub>3</sub></td><td>0.27 ± 0.14</td><td>0.55</td><td>0.18</td><td>0.07</td><td>57.1 ± 0.40</td><td>0.47</td><td>0.32</td><td>0.52</td><td>1.06</td></tr><tr><td>FeO</td><td>1.56 ± 0.57</td><td>2.21</td><td>0.60</td><td>0.66</td><td>29.3 ± 0.47</td><td>16.1</td><td>23.0 ± 1.3</td><td>9.3 ± 1.1</td><td>8.8 ± 0.8</td></tr><tr><td>MnO</td><td>n.d.</td><td>&lt;0.02</td><td>n.d.</td><td>n.d.</td><td>0.96 ± 0.15</td><td>0.35</td><td>0.51</td><td>0.21</td><td>0.37</td></tr><tr><td>MgO</td><td>0.30 ± 0.46</td><td>5.8</td><td>0.05</td><td>3.6</td><td>3.1 ± 0.34</td><td>23.7</td><td>36.4 ± 1.4</td><td>15.1 ± 0.9</td><td>15.5 ± 0.8</td></tr><tr><td>CaO</td><td>0.51 ± 0.58</td><td>15.9</td><td>51.2</td><td>45.6</td><td>0.11</td><td>3.4</td><td>0.19</td><td>2.7 ± 0.4</td><td>17.2 ± 1.3</td></tr><tr><td>Na<sub>2</sub>O</td><td>10.5 ± 2.7</td><td>n.d.</td><td>0.41</td><td>2.88</td><td>0.22</td><td>2.49</td><td>0.44</td><td>5.3 ± 0.5</td><td>0.44</td></tr><tr><td>K<sub>2</sub>O</td><td>5.0 ± 2.7</td><td>n.d.</td><td>0.06</td><td>n.d.</td><td>&lt;0.02</td><td>0.12</td><td>&lt;0.01</td><td>0.25</td><td>n.d.</td></tr><tr><td>P<sub>2</sub>O<sub>5</sub></td><td>0.16 ± 0.07</td><td>n.d.</td><td>41.4</td><td>47.3</td><td>&lt;0.03</td><td>Ni: 0.09</td><td>n.a.</td><td>n.a.</td><td>n.a.</td></tr><tr><td>Total</td><td>99.43</td><td>100.01</td><td>99.91<sup>a</sup></td><td>100.22</td><td>99.50<sup>b</sup></td><td>98.39</td><td>101.02</td><td>99.86</td><td>99.59</td></tr></tbody><tfoot><tr><td colspan="10">Note: Most chromites from the H6 fragment. All data in wt%.</td></tr><tr><td colspan="10">Bold indicates the results of this study and italics indicates the mean of many literature data.</td></tr><tr><td colspan="10">Abbreviations: n, number of analyses; n.a., not analyzed; n.d., not detected; Plag, plagioclase.; Ppx, pyroxene.</td></tr><tr><td colspan="10"><sup>a</sup>Contains 5.8 wt% Cl.</td></tr><tr><td colspan="10"><sup>b</sup>Not analyzed for Zn, V, etc., and not checked for Fe<sup>3+</sup>.</td></tr></tfoot></table>

<table><caption>TABLE 3. Mean chemical composition of metals and sulfide (troilite) from Elmshorn fragment E03.</caption><thead><tr><th rowspan="2"></th><th colspan="4">Elmshorn (bulk sample)</th><th colspan="2">Elmshorn (H6 fragment)</th></tr><tr><th>Kamacite (n = 26)</th><th>Taenite (n = 5)</th><th>Troilite (n = 12)</th><th>Tetrataenite (n = 1)</th><th>Kamacite (n = 5)</th><th>Troilite (n = 3)</th></tr></thead><tbody><tr><td>Fe</td><td>93.3 ± 0.96</td><td>70.1 ± 10.2</td><td>61.7 ± 0.55</td><td>48.5</td><td>93.0 ± 1.3</td><td>62.6 ± 0.1</td></tr><tr><td>Co</td><td>0.69 ± 0.06</td><td>0.35 ± 0.23</td><td>0.10 ± 0.03</td><td>0.12</td><td>0.71 ± 0.05</td><td>0.08 ± 0.03</td></tr><tr><td>Ni</td><td>5.4 ± 1.33</td><td>29.2 ± 10.2</td><td>0.03 ± 0.03</td><td>49.2</td><td>5.8 ± 1.3</td><td>&lt;0.03</td></tr><tr><td>S</td><td>n.d.</td><td>n.d.</td><td>35.9 ± 0.28</td><td>n.d.</td><td>n.d.</td><td>36.0 ± 0.3</td></tr><tr><td>Total</td><td>99.39</td><td>99.65</td><td>97.73</td><td>97.82</td><td>99.51</td><td>98.71</td></tr></tbody></table>

crystals (olivine, pyroxenes) embedded in a fine-grained groundmass. The bulk composition of the so-called melt clast is given in Table 2. The almost equilibrated olivines (Fa<sub>26</sub>; Table 2) contain considerable concentrations of Al<sub>2</sub>O<sub>3</sub> (1.03 wt%) and Na<sub>2</sub>O (0.44 wt%). Also, the coexisting pyroxenes have unusual compositions with remarkably high concentrations of Al<sub>2</sub>O<sub>3</sub> and Na<sub>2</sub>O (Table 2), which may be the result of contamination due to the fine-grained intergrowths of different phases (Figure S4).

As stated earlier during randomly selected mineral analysis, olivines with Fa contents above 20 (up to 24) mol % were frequently encountered, and a detailed search revealed olivine compositions ranging from Fa<sub>&lt;1</sub> to Fa<sub>32</sub>. The olivines with highly variable Fa contents can be assigned to type 3 fragments, in which chondrules have glassy mesostasis (Figures 5 and 6) and strongly zoned

olivine and low-Ca pyroxene crystals (Figure 6d). In BSE images from the Elmshorn main portion, areas were detected that show up as slightly lighter gray than others (Figure S5). Detailed studies revealed that they represent distinct clasts with almost equilibrated olivine compositions (often type 3.8–4). The mean Fa contents are well above 20 mole%, indicating an H/L or L chondrite origin (Figure 8). Some fragments were identified and analyzed with almost equilibrated olivines having (mean) Fa<sub>21.0±1.2</sub>, Fa<sub>21.5±1.0</sub>, Fa<sub>22.0±1.3</sub>, Fa<sub>21.5±1.4</sub>, and Fa<sub>20.9±0.7</sub> (Figure 8). These fragments must be of an intermediate H/L chondrite heritage.

As mentioned earlier, the studied section of the second analyzed stone (E07) has lithic clasts with abundant olivine of Fa<sub>21–23</sub> (Figure 8b). These olivines are significantly FeO richer than those in the E03 piece. Thus, the typical H chondrite lithologies (with Fa<sub>18–20</sub>) are less
<table><caption>TABLE 2. Chemical composition of minor phases in the Elmshorn breccia E03 as well as the bulk composition and (contaminated) phases of the melt fragment M from E03 (Figure 5f and Figure S1). Mesostasis and fassaite from the Na,Al-rich chondrule shown in Figure 6c,d.</caption><thead><tr><th rowspan="2"></th><th rowspan="2">Mesostasis<br>(bulk) (n = 5)</th><th rowspan="2">Fassaite<br>(mean)<br>(n = 2)</th><th rowspan="2">Apatite<br>(n = 5)<sup>a</sup></th><th rowspan="2">Merrillite<br>(n = 6)</th><th rowspan="2">Chromite<br>(n = 8)</th><th colspan="4">Melt fragment M</th></tr><tr><th>Bulk chem<br>(n = 397)</th><th>Olivine<br>(n = 20)</th><th>Low-Ca<br>pyroxene<br>(n = 16)</th><th>Ca<br>pyroxene<br>(n = 6)</th></tr></thead><tbody><tr><td>SiO<sub>2</sub></td><td>57.5 ± 2.8</td><td>52.7</td><td>0.14</td><td>0.09</td><td>0.23 ± 0.15</td><td>45.0</td><td>39.0 ± 0.4</td><td>54.1 ± 0.9</td><td>49.3 ± 0.7</td></tr><tr><td>TiO<sub>2</sub></td><td>0.90 ± 0.08</td><td>0.93</td><td>&lt;0.03</td><td>&lt;0.01</td><td>2.33 ± 0.27</td><td>0.27</td><td>0.12</td><td>0.38</td><td>0.72</td></tr><tr><td>Al<sub>2</sub>O<sub>3</sub></td><td>23.0 ± 1.4</td><td>21.9</td><td>&lt;0.04</td><td>&lt;0.01</td><td>6.1 ± 0.64</td><td>6.4</td><td>1.03 ± 0.34</td><td>12.0 ± 0.6</td><td>6.2 ± 0.9</td></tr><tr><td>Cr<sub>2</sub>O<sub>3</sub></td><td>0.27 ± 0.14</td><td>0.55</td><td>0.18</td><td>0.07</td><td>57.1 ± 0.40</td><td>0.47</td><td>0.32</td><td>0.52</td><td>1.06</td></tr><tr><td>FeO</td><td>1.56 ± 0.57</td><td>2.21</td><td>0.60</td><td>0.66</td><td>29.3 ± 0.47</td><td>16.1</td><td>23.0 ± 1.3</td><td>9.3 ± 1.1</td><td>8.8 ± 0.8</td></tr><tr><td>MnO</td><td>n.d.</td><td>&lt;0.02</td><td>n.d.</td><td>n.d.</td><td>0.96 ± 0.15</td><td>0.35</td><td>0.51</td><td>0.21</td><td>0.37</td></tr><tr><td>MgO</td><td>0.30 ± 0.46</td><td>5.8</td><td>0.05</td><td>3.6</td><td>3.1 ± 0.34</td><td>23.7</td><td>36.4 ± 1.4</td><td>15.1 ± 0.9</td><td>15.5 ± 0.8</td></tr><tr><td>CaO</td><td>0.51 ± 0.58</td><td>15.9</td><td>51.2</td><td>45.6</td><td>0.11</td><td>3.4</td><td>0.19</td><td>2.7 ± 0.4</td><td>17.2 ± 1.3</td></tr><tr><td>Na<sub>2</sub>O</td><td>10.5 ± 2.7</td><td>n.d.</td><td>0.41</td><td>2.88</td><td>0.22</td><td>2.49</td><td>0.44</td><td>5.3 ± 0.5</td><td>0.44</td></tr><tr><td>K<sub>2</sub>O</td><td>5.0 ± 2.7</td><td>n.d.</td><td>0.06</td><td>n.d.</td><td>&lt;0.02</td><td>0.12</td><td>&lt;0.01</td><td>0.25</td><td>n.d.</td></tr><tr><td>P<sub>2</sub>O<sub>5</sub></td><td>0.16 ± 0.07</td><td>n.d.</td><td>41.4</td><td>47.3</td><td>&lt;0.03</td><td>Ni: 0.09</td><td>n.a.</td><td>n.a.</td><td>n.a.</td></tr><tr><td>Total</td><td>99.43</td><td>100.01</td><td>99.91<sup>a</sup></td><td>100.22</td><td>99.50<sup>b</sup></td><td>98.39</td><td>101.02</td><td>99.86</td><td>99.59</td></tr></tbody><tfoot><tr><td colspan="10"><em>Note:</em> Most chromites from the H6 fragment. All data in wt%.</td></tr><tr><td colspan="10">Bold indicates the results of this study and italics indicates the mean of many literature data.</td></tr><tr><td colspan="10">Abbreviations: n, number of analyses; n.a., not analyzed; n.d., not detected; Plag, plagioclase.; Ppx, pyroxene.</td></tr><tr><td colspan="10"><sup>a</sup>Contains 5.8 wt% Cl.</td></tr><tr><td colspan="10"><sup>b</sup>Not analyzed for Zn, V, etc., and not checked for Fe<sup>3+</sup>.</td></tr></tfoot></table>

<table><caption>TABLE 3. Mean chemical composition of metals and sulfide (troilite) from Elmshorn fragment E03.</caption><thead><tr><th rowspan="2"></th><th colspan="4">Elmshorn (bulk sample)</th><th colspan="2">Elmshorn (H6 fragment)</th></tr><tr><th>Kamacite (n = 26)</th><th>Taenite (n = 5)</th><th>Troilite (n = 12)</th><th>Tetrataenite (n = 1)</th><th>Kamacite (n = 5)</th><th>Troilite (n = 3)</th></tr></thead><tbody><tr><td>Fe</td><td>93.3 ± 0.96</td><td>70.1 ± 10.2</td><td>61.7 ± 0.55</td><td>48.5</td><td>93.0 ± 1.3</td><td>62.6 ± 0.1</td></tr><tr><td>Co</td><td>0.69 ± 0.06</td><td>0.35 ± 0.23</td><td>0.10 ± 0.03</td><td>0.12</td><td>0.71 ± 0.05</td><td>0.08 ± 0.03</td></tr><tr><td>Ni</td><td>5.4 ± 1.33</td><td>29.2 ± 10.2</td><td>0.03 ± 0.03</td><td>49.2</td><td>5.8 ± 1.3</td><td>&lt;0.03</td></tr><tr><td>S</td><td>n.d.</td><td>n.d.</td><td>35.9 ± 0.28</td><td>n.d.</td><td>n.d.</td><td>36.0 ± 0.3</td></tr><tr><td>Total</td><td>99.39</td><td>99.65</td><td>97.73</td><td>97.82</td><td>99.51</td><td>98.71</td></tr></tbody></table>

crystals (olivine, pyroxenes) embedded in a fine-grained groundmass. The bulk composition of the so-called melt clast is given in Table 2. The almost equilibrated olivines (Fa<sub>26</sub>; Table 2) contain considerable concentrations of Al<sub>2</sub>O<sub>3</sub> (1.03 wt%) and Na<sub>2</sub>O (0.44 wt%). Also, the coexisting pyroxenes have unusual compositions with remarkably high concentrations of Al<sub>2</sub>O<sub>3</sub> and Na<sub>2</sub>O (Table 2), which may be the result of contamination due to the fine-grained intergrowths of different phases (Figure S4).

As stated earlier during randomly selected mineral analysis, olivines with Fa contents above 20 (up to 24) mol % were frequently encountered, and a detailed search revealed olivine compositions ranging from Fa<sub>&lt;1</sub> to Fa<sub>32</sub>. The olivines with highly variable Fa contents can be assigned to type 3 fragments, in which chondrules have glassy mesostasis (Figures 5 and 6) and strongly zoned

olivine and low-Ca pyroxene crystals (Figure 6d). In BSE images from the Elmshorn main portion, areas were detected that show up as slightly lighter gray than others (Figure S5). Detailed studies revealed that they represent distinct clasts with almost equilibrated olivine compositions (often type 3.8–4). The mean Fa contents are well above 20 mole%, indicating an H/L or L chondrite origin (Figure 8). Some fragments were identified and analyzed with almost equilibrated olivines having (mean) Fa<sub>21.0±1.2</sub>, Fa<sub>21.5±1.0</sub>, Fa<sub>22.0±1.3</sub>, Fa<sub>21.5±1.4</sub>, and Fa<sub>20.9±0.7</sub> (Figure 8). These fragments must be of an intermediate H/L chondrite heritage.

As mentioned earlier, the studied section of the second analyzed stone (E07) has lithic clasts with abundant olivine of Fa<sub>21–23</sub> (Figure 8b). These olivines are significantly FeO richer than those in the E03 piece. Thus, the typical H chondrite lithologies (with Fa<sub>18–20</sub>) are less
<figure><img src="image_6.png" /><figcaption>FIGURE 5. Lithologies from E03: (a) type 6 clast in transmitted polarized light (crossed nicols); (b) same clast as in (a) in-plane polarized light; (c) type 3 fragment with chondrules containing brownish mesostasis glass (arrows; plane polarized light); (d) type 4 fragment enclosed in the fine-grained, clastic matrix; the dashed line indicates the boundary of the clast (plane polarized light); (e) large association with apatite (Ap), olivine (Ol; ~Fa~17.5), and merrillite (Mer) in the matrix of Elmshorn (BSE image); (f) large clast (fragment M) of an unusual melt with skeletal crystals (partly olivine [Fa~26]) embedded in a fine-grained groundmass (plane polarized light).</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>FIGURE 5. Lithologies from E03: (a) type 6 clast in transmitted polarized light (crossed nicols); (b) same clast as in (a) in-plane polarized light; (c) type 3 fragment with chondrules containing brownish mesostasis glass (arrows; plane polarized light); (d) type 4 fragment enclosed in the fine-grained, clastic matrix; the dashed line indicates the boundary of the clast (plane polarized light); (e) large association with apatite (Ap), olivine (Ol; ~Fa~17.5), and merrillite (Mer) in the matrix of Elmshorn (BSE image); (f) large clast (fragment M) of an unusual melt with skeletal crystals (partly olivine [Fa~26]) embedded in a fine-grained groundmass (plane polarized light).</figcaption></figure>
<figure><img src="image_7.png" /></figure>

FIGURE 6. Chondrules from E03: (a) olivine- and pyroxene-rich (POP) chondrule; (b) barred olivine (BO) chondrule with interstitial mesostasis glass (brownish); (c) Na,Al-rich chondrule with olivine and pyroxenes enclosed in Al-rich brownish mesostasis; (d) same chondrule as in (c), arrows indicate the strong zoning of olivine (Fa<1-27) as well as the occurrence of Ca pyroxene (fassaite [Fas]); (e) BO chondrule; (f) radial pyroxene (RP) chondrule. Figures in transmitted light except for the BSE image in (d).
<figure><img src="image_8.png" /></figure>

FIGURE 6. Chondrules from E03: (a) olivine- and pyroxene-rich (POP) chondrule; (b) barred olivine (BO) chondrule with interstitial mesostasis glass (brownish); (c) Na,Al-rich chondrule with olivine and pyroxenes enclosed in Al-rich brownish mesostasis; (d) same chondrule as in (c), arrows indicate the strong zoning of olivine (Fa<1-27) as well as the occurrence of Ca pyroxene (fassaite [Fas]); (e) BO chondrule; (f) radial pyroxene (RP) chondrule. Figures in transmitted light except for the BSE image in (d).
<table><caption>TABLE 4. Oxygen isotope composition of eight aliquots from the Elmshorn chondrite breccia. Four samples of the shattered rock E03 were analyzed as well as four aliquots of E07 found to the northeast of E03.</caption><thead><tr><th>Meteorite</th><th>Sample</th><th>Mass (mg)</th><th>δ<sup>17</sup>O</th><th>δ<sup>18</sup>O</th><th>Δ<sup>17</sup>O</th></tr></thead><tbody><tr><td>Elmshorn</td><td>E03: sample-1</td><td>2.251</td><td>2.614</td><td>3.831</td><td>0.592</td></tr><tr><td>Elmshorn</td><td>E03: sample-2</td><td>2.062</td><td>2.937</td><td>4.051</td><td>0.799</td></tr><tr><td>Elmshorn</td><td>E03: sample-3</td><td>2.144</td><td>2.667</td><td>4.018</td><td>0.546</td></tr><tr><td>Elmshorn</td><td>E03: sample-4</td><td>2.037</td><td>3.079</td><td>4.511</td><td>0.698</td></tr><tr><td></td><td>Mean</td><td></td><td>2.824</td><td>4.103</td><td>0.659</td></tr><tr><td>Elmshorn</td><td>E07: sample-1</td><td>2.090</td><td>2.788</td><td>3.735</td><td>0.815</td></tr><tr><td>Elmshorn</td><td>E07: sample-2</td><td>2.246</td><td>2.839</td><td>4.097</td><td>0.676</td></tr><tr><td>Elmshorn</td><td>E07: sample-3</td><td>2.153</td><td>2.845</td><td>4.187</td><td>0.635</td></tr><tr><td>Elmshorn</td><td>E07: sample-4</td><td>2.030</td><td>2.754</td><td>4.018</td><td>0.634</td></tr><tr><td></td><td>Mean</td><td></td><td>2.807</td><td>4.009</td><td>0.690</td></tr></tbody></table>

abundant in sample E07 than in sample E03. Some typical images from sample E07 are given in Figure S6.

## Shock Metamorphism of Elmshorn

The studied thin sections of the Elmshorn OC clearly show that the rock is a complex breccia. In order to determine the shock degree of a bulk rock breccia, the fragment with the lowest degree of shock has to be considered. Thus, Elmshorn has a shock degree of S2 (C-S2) considering the undulatory extinction of olivines in many lithic clasts (Bischoff, Schleiting, et al., 2019; Bischoff & Stöffler, 1992; Stöffler et al., 1991, 2018). Since the brecciated character of Elmshorn is easily detectable in the hand specimen and clearly visible in thin sections (Figure 4), individual clasts certainly exist that have a higher degree of shock metamorphism than S2. Fragments with olivines having planar fractures exist as well as fragments showing typical characteristics of shock darkening (Figure 9c) or clasts having internal shock veins. We also detected thin, but several millimeter-long metal-sulfide associations that may have been formed due to shock processes (Figure 9f, Figures S1 and S2) as well as porous vein-like areas with unusual metal and sulfide constituents (Figure 9e). Finally, clasts of impact melt veins or pools (Figure 9a) and the dark clasts with the internal, fine-grained distribution of metals and sulfides (Figure 9b) indicate a complex impact-related history.

## Oxygen Isotopes

The O isotope compositions of the eight analyzed chips from two different fragments are listed in Table 4. The sample E03 is dominated by H chondrite components, and sample E07 has physical properties (density, MS) consistent with L chondrites. However, all data for the two Elmshorn fragments plot within the field of H chondrites and are indistinguishable from each other (Figure 10).

## Bulk Chemical Characteristics

For most elements, the chemical compositions of Elmshorn (Table 5) are close to the compositions of the recently analyzed meteorites Ejby, Blaubeuren, Braunschweig, Antonin, L'Aigle, and Saint-Pierre-le-Viger and are also similar to the mean composition of L and H chondrites (Bartoschewitz et al., 2017; Bischoff, Barrat, et al., 2019; Bischoff, Patzek, et al., 2022a; Bischoff et al., 2023; Lodders & Fegley, 1998). The relatively high concentrations of Fe, Co, and Ni in the Elmshorn sample E03 are clearly more related to other H chondrites than to L chondrites.

## Titanium and Chromium Isotopes

The nucleosynthetic Ti isotope data of Elmshorn, BHVO-2, and Forest Vale are listed in Table 6. The Ti isotope composition of Elmshorn shows an isotopic deficit in $\epsilon^{46}$Ti and $\epsilon^{50}$Ti data relative to Earth ($\epsilon^{i}=0$), which agrees with the data of the Forest Vale OC (H4) and generally with those of OCs from the literature (Figures 11 and 12). The nucleosynthetic Cr isotope values for Elmshorn and DTS-2 are shown in Table 6. The Elmshorn Cr isotope data show an excess in $\epsilon^{53}$Cr and a deficit in $\epsilon^{54}$Cr, relative to the terrestrial composition, again in agreement with OC literature values (Figure 12). The Ti and Cr isotope data thus indicate that the Elmshorn meteorite originated in the NC (noncarbonaceous meteorite) reservoir in the inner solar system and that it belongs to the group of OCs.

## Noble Gas Composition

The presence of a solar wind component can be excluded for both aliquots because trapped components are not distinguishable for both He and Ne (Table 7a). Thus, Elmshorn is a fragmental breccia. As stated earlier, the Ar values are composed of a mixture between both cosmogenic and trapped Ar with the addition of $^{40}$Ar$_{rad}$ (Table 7b). The trapped component cannot be further narrowed down since the Q and air $^{36}$Ar/$^{38}$Ar ratios are isotopically too close. The Kr and Xe isotopes show mainly trapped signatures (Table 7b,c). The Xe-trapped component for the two aliquots is dominated by Q, as shown in Figure 13, which suggests that both Ar and Kr are also from phase Q. The noticeable deviation from the Q composition of the $^{124}$Xe/$^{132}$Xe ratios for both samples implies a small cosmogenic influence. Both Elmshorn 1 and 2 (both subsamples from E03) show short-lived $^{129}$I-derived $^{129}$Xe excesses. This feature is usually seen in OCs of types 5 or 6 (e.g., Alaerts et al., 1979; Moniot, 1980).
<table><caption>TABLE 4. Oxygen isotope composition of eight aliquots from the Elmshorn chondrite breccia. Four samples of the shattered rock E03 were analyzed as well as four aliquots of E07 found to the northeast of E03.</caption><thead><tr><th>Meteorite</th><th>Sample</th><th>Mass (mg)</th><th>δ<sup>17</sup>O</th><th>δ<sup>18</sup>O</th><th>Δ<sup>17</sup>O</th></tr></thead><tbody><tr><td>Elmshorn</td><td>E03: sample-1</td><td>2.251</td><td>2.614</td><td>3.831</td><td>0.592</td></tr><tr><td>Elmshorn</td><td>E03: sample-2</td><td>2.062</td><td>2.937</td><td>4.051</td><td>0.799</td></tr><tr><td>Elmshorn</td><td>E03: sample-3</td><td>2.144</td><td>2.667</td><td>4.018</td><td>0.546</td></tr><tr><td>Elmshorn</td><td>E03: sample-4</td><td>2.037</td><td>3.079</td><td>4.511</td><td>0.698</td></tr><tr><td></td><td>Mean</td><td></td><td>2.824</td><td>4.103</td><td>0.659</td></tr><tr><td>Elmshorn</td><td>E07: sample-1</td><td>2.090</td><td>2.788</td><td>3.735</td><td>0.815</td></tr><tr><td>Elmshorn</td><td>E07: sample-2</td><td>2.246</td><td>2.839</td><td>4.097</td><td>0.676</td></tr><tr><td>Elmshorn</td><td>E07: sample-3</td><td>2.153</td><td>2.845</td><td>4.187</td><td>0.635</td></tr><tr><td>Elmshorn</td><td>E07: sample-4</td><td>2.030</td><td>2.754</td><td>4.018</td><td>0.634</td></tr><tr><td></td><td>Mean</td><td></td><td>2.807</td><td>4.009</td><td>0.690</td></tr></tbody></table>

abundant in sample E07 than in sample E03. Some typical images from sample E07 are given in Figure S6.

## Shock Metamorphism of Elmshorn

The studied thin sections of the Elmshorn OC clearly show that the rock is a complex breccia. In order to determine the shock degree of a bulk rock breccia, the fragment with the lowest degree of shock has to be considered. Thus, Elmshorn has a shock degree of S2 (C-S2) considering the undulatory extinction of olivines in many lithic clasts (Bischoff, Schleiting, et al., 2019; Bischoff & Stöffler, 1992; Stöffler et al., 1991, 2018). Since the brecciated character of Elmshorn is easily detectable in the hand specimen and clearly visible in thin sections (Figure 4), individual clasts certainly exist that have a higher degree of shock metamorphism than S2. Fragments with olivines having planar fractures exist as well as fragments showing typical characteristics of shock darkening (Figure 9c) or clasts having internal shock veins. We also detected thin, but several millimeter-long metal-sulfide associations that may have been formed due to shock processes (Figure 9f, Figures S1 and S2) as well as porous vein-like areas with unusual metal and sulfide constituents (Figure 9e). Finally, clasts of impact melt veins or pools (Figure 9a) and the dark clasts with the internal, fine-grained distribution of metals and sulfides (Figure 9b) indicate a complex impact-related history.

## Oxygen Isotopes

The O isotope compositions of the eight analyzed chips from two different fragments are listed in Table 4. The sample E03 is dominated by H chondrite components, and sample E07 has physical properties (density, MS) consistent with L chondrites. However, all data for the two Elmshorn fragments plot within the field of H chondrites and are indistinguishable from each other (Figure 10).

## Bulk Chemical Characteristics

For most elements, the chemical compositions of Elmshorn (Table 5) are close to the compositions of the recently analyzed meteorites Ejby, Blaubeuren, Braunschweig, Antonin, L'Aigle, and Saint-Pierre-le-Viger and are also similar to the mean composition of L and H chondrites (Bartoschewitz et al., 2017; Bischoff, Barrat, et al., 2019; Bischoff, Patzek, et al., 2022a; Bischoff et al., 2023; Lodders & Fegley, 1998). The relatively high concentrations of Fe, Co, and Ni in the Elmshorn sample E03 are clearly more related to other H chondrites than to L chondrites.

## Titanium and Chromium Isotopes

The nucleosynthetic Ti isotope data of Elmshorn, BHVO-2, and Forest Vale are listed in Table 6. The Ti isotope composition of Elmshorn shows an isotopic deficit in $\epsilon^{46}$Ti and $\epsilon^{50}$Ti data relative to Earth ($\epsilon^{i}=0$), which agrees with the data of the Forest Vale OC (H4) and generally with those of OCs from the literature (Figures 11 and 12). The nucleosynthetic Cr isotope values for Elmshorn and DTS-2 are shown in Table 6. The Elmshorn Cr isotope data show an excess in $\epsilon^{53}$Cr and a deficit in $\epsilon^{54}$Cr, relative to the terrestrial composition, again in agreement with OC literature values (Figure 12). The Ti and Cr isotope data thus indicate that the Elmshorn meteorite originated in the NC (noncarbonaceous meteorite) reservoir in the inner solar system and that it belongs to the group of OCs.

## Noble Gas Composition

The presence of a solar wind component can be excluded for both aliquots because trapped components are not distinguishable for both He and Ne (Table 7a). Thus, Elmshorn is a fragmental breccia. As stated earlier, the Ar values are composed of a mixture between both cosmogenic and trapped Ar with the addition of $^{40}$Ar$_{rad}$ (Table 7b). The trapped component cannot be further narrowed down since the Q and air $^{36}$Ar/$^{38}$Ar ratios are isotopically too close. The Kr and Xe isotopes show mainly trapped signatures (Table 7b,c). The Xe-trapped component for the two aliquots is dominated by Q, as shown in Figure 13, which suggests that both Ar and Kr are also from phase Q. The noticeable deviation from the Q composition of the $^{124}$Xe/$^{132}$Xe ratios for both samples implies a small cosmogenic influence. Both Elmshorn 1 and 2 (both subsamples from E03) show short-lived $^{129}$I-derived $^{129}$Xe excesses. This feature is usually seen in OCs of types 5 or 6 (e.g., Alaerts et al., 1979; Moniot, 1980).
<table><caption>TABLE 5. Major and trace element abundances of the anomalous (an) Elmshorn H3-6 chondrite breccia (sample E03). The mean of about 1600 randomly obtained microprobe analyses on two Elmshorn samples revealed Al and Si concentrations of 1.38 and 18.6 wt%, respectively.</caption><thead><tr><th>Element</th><th>Ejby H5/6</th><th>Blaubeuren H5-6</th><th>Mean H</th><th>Elmshorn H3-6-an</th><th>Mean L</th><th>Braunschweig L6</th><th>Antonin L4-5</th></tr></thead><tbody><tr><td>Al</td><td>1.10<sup>a</sup></td><td>1.05<sup>a</sup></td><td><strong>1.06<sup>a</sup></strong></td><td></td><td><strong>1.16<sup>a</sup></strong></td><td>1.159<sup>a</sup></td><td>1.01<sup>a</sup></td></tr><tr><td>Fe</td><td>28.7<sup>a</sup></td><td>24.5<sup>a</sup></td><td><strong>27.2<sup>a</sup></strong></td><td><strong>31.7<sup>a</sup></strong></td><td><strong>21.8<sup>a</sup></strong></td><td>21.6<sup>a</sup></td><td>22.0<sup>a</sup></td></tr><tr><td>Mg</td><td>14.99<sup>a</sup></td><td>13.28<sup>a</sup></td><td><strong>14.1<sup>a</sup></strong></td><td><strong>12.6<sup>a</sup></strong></td><td><strong>14.9<sup>a</sup></strong></td><td>15.0<sup>a</sup></td><td>14.4<sup>a</sup></td></tr><tr><td>Na</td><td>0.67<sup>a</sup></td><td>0.25<sup>a</sup></td><td><strong>0.61<sup>a</sup></strong></td><td><strong>0.60<sup>a</sup></strong></td><td><strong>0.69<sup>a</sup></strong></td><td>0.712<sup>a</sup></td><td>0.65<sup>a</sup></td></tr><tr><td>Ni</td><td>2.11<sup>a</sup></td><td>1.57<sup>a</sup></td><td><strong>1.71<sup>a</sup></strong></td><td><strong>2.05<sup>a</sup></strong></td><td><strong>1.24<sup>a</sup></strong></td><td>1.23<sup>a</sup></td><td>1.56<sup>a</sup></td></tr><tr><td>P</td><td>1309</td><td>812</td><td><strong>1200</strong></td><td><strong>1177</strong></td><td><strong>1030</strong></td><td>1310</td><td>905</td></tr><tr><td>K</td><td>950</td><td>421</td><td><strong>780</strong></td><td><strong>997</strong></td><td><strong>920</strong></td><td>1021</td><td>873</td></tr><tr><td>Ca</td><td>1.28<sup>a</sup></td><td>1.02<sup>a</sup></td><td><strong>1.22<sup>a</sup></strong></td><td><strong>1.08<sup>a</sup></strong></td><td><strong>1.33<sup>a</sup></strong></td><td>1.41<sup>a</sup></td><td>1.21<sup>a</sup></td></tr><tr><td>Sc</td><td>8.7</td><td>7.39</td><td><strong>7.8</strong></td><td><strong>4.4</strong></td><td><strong>8.1</strong></td><td>10.01</td><td>8.52</td></tr><tr><td>Ti</td><td>620</td><td>480</td><td><strong>630</strong></td><td><strong>581</strong></td><td><strong>670</strong></td><td>644</td><td>610</td></tr><tr><td>V</td><td>74</td><td>49.4</td><td><strong>73</strong></td><td><strong>73</strong></td><td><strong>75</strong></td><td>70.09</td><td>62.1</td></tr><tr><td>Cr</td><td>3118</td><td>3597</td><td><strong>3500</strong></td><td><strong>3573</strong></td><td><strong>3690</strong></td><td>3804</td><td>3048</td></tr><tr><td>Mn</td><td>2606</td><td>2036</td><td><strong>2340</strong></td><td><strong>2417</strong></td><td><strong>2590</strong></td><td>0.267<sup>a</sup></td><td>2478</td></tr><tr><td>Co</td><td>715</td><td>621</td><td><strong>830</strong></td><td><strong>1105</strong></td><td><strong>580</strong></td><td>601</td><td>582</td></tr><tr><td>Cu</td><td>73.1</td><td></td><td></td><td><strong>84</strong></td><td><strong>90</strong></td><td></td><td>84.6</td></tr><tr><td>Zn</td><td>43.5</td><td>25.6</td><td><strong>47</strong></td><td><strong>57</strong></td><td><strong>57</strong></td><td>43.96</td><td>42.4</td></tr><tr><td>Ga</td><td>5.06</td><td>4.46</td><td><strong>6.0</strong></td><td><strong>5.8</strong></td><td><strong>5.4</strong></td><td>5.05</td><td>4.81</td></tr><tr><td>Rb</td><td>2.88</td><td>1.17</td><td><strong>2.3</strong></td><td><strong>5.8</strong></td><td><strong>2.8</strong></td><td>3.06</td><td>2.59</td></tr><tr><td>Sr</td><td>10.9</td><td>5.58</td><td><strong>8.8</strong></td><td><strong>9.4</strong></td><td><strong>11</strong></td><td>11.34</td><td>10.5</td></tr><tr><td>Y</td><td>2.97</td><td>1.65</td><td><strong>2.0</strong></td><td><strong>2.1</strong></td><td><strong>1.8</strong></td><td>2.32</td><td>1.98</td></tr><tr><td>Zr</td><td>4.63</td><td>4.47</td><td><strong>7.3</strong></td><td><strong>4.8</strong></td><td><strong>6.4</strong></td><td>6.48</td><td>5.02</td></tr><tr><td>Nb</td><td>0.381</td><td>0.399</td><td><strong>0.4</strong></td><td><strong>0.59</strong></td><td><strong>0.4</strong></td><td>0.46</td><td>0.43</td></tr><tr><td>Cs</td><td>0.0178</td><td></td><td></td><td><strong>0.32</strong></td><td></td><td>0.048</td><td>0.030</td></tr><tr><td>Ba</td><td>3.49</td><td>2.06</td><td><strong>4.4</strong></td><td><strong>2.90</strong></td><td><strong>4.1</strong></td><td>3.78</td><td>3.53</td></tr><tr><td>La</td><td>0.344</td><td>0.226</td><td><strong>0.301</strong></td><td><strong>0.295</strong></td><td><strong>0.318</strong></td><td>0.328</td><td>0.277</td></tr><tr><td>Ce</td><td>0.885</td><td>0.599</td><td><strong>0.763</strong></td><td><strong>0.777</strong></td><td><strong>0.970</strong></td><td>0.873</td><td>0.711</td></tr><tr><td>Pr</td><td>0.132</td><td>0.089</td><td><strong>0.120</strong></td><td><strong>0.116</strong></td><td><strong>0.140</strong></td><td>0.128</td><td>0.107</td></tr><tr><td>Nd</td><td>0.658</td><td>0.450</td><td><strong>0.581</strong></td><td><strong>0.593</strong></td><td><strong>0.700</strong></td><td>0.649</td><td>0.538</td></tr><tr><td>Sm</td><td>0.211</td><td>0.147</td><td><strong>0.194</strong></td><td><strong>0.188</strong></td><td><strong>0.303</strong></td><td>0.218</td><td>0.176</td></tr><tr><td>Eu</td><td>0.072</td><td>0.064</td><td><strong>0.074</strong></td><td><strong>0.069</strong></td><td><strong>0.080</strong></td><td>0.0827</td><td>0.079</td></tr><tr><td>Gd</td><td>0.303</td><td>0.204</td><td><strong>0.275</strong></td><td><strong>0.266</strong></td><td><strong>0.317</strong></td><td>0.30</td><td>0.243</td></tr><tr><td>Tb</td><td>0.0548</td><td>0.0348</td><td><strong>0.049</strong></td><td><strong>0.048</strong></td><td><strong>0.059</strong></td><td>0.0549</td><td>0.045</td></tr><tr><td>Dy</td><td>0.369</td><td>0.262</td><td><strong>0.305</strong></td><td><strong>0.330</strong></td><td><strong>0.372</strong></td><td>0.378</td><td>0.306</td></tr><tr><td>Ho</td><td>0.0815</td><td>0.0586</td><td><strong>0.074</strong></td><td><strong>0.073</strong></td><td><strong>0.089</strong></td><td>0.0835</td><td>0.069</td></tr><tr><td>Er</td><td>0.239</td><td>0.174</td><td><strong>0.213</strong></td><td><strong>0.216</strong></td><td><strong>0.252</strong></td><td>0.250</td><td>0.302</td></tr><tr><td>Tm</td><td>0.0356</td><td>0.0270</td><td><strong>0.033</strong></td><td></td><td><strong>0.038</strong></td><td></td><td>0.031</td></tr><tr><td>Yb</td><td>0.228</td><td>0.178</td><td><strong>0.203</strong></td><td><strong>0.212</strong></td><td><strong>0.226</strong></td><td>0.256</td><td>0.206</td></tr><tr><td>Lu</td><td>0.0345</td><td>0.0274</td><td><strong>0.033</strong></td><td><strong>0.031</strong></td><td><strong>0.034</strong></td><td>0.0392</td><td>0.0313</td></tr><tr><td>Hf</td><td>0.135</td><td>0.135</td><td><strong>0.150</strong></td><td><strong>0.135</strong></td><td><strong>0.170</strong></td><td>0.197</td><td>0.152</td></tr><tr><td>Ta</td><td>0.0107</td><td>0.0163</td><td><strong>0.021</strong></td><td><strong>0.018</strong></td><td><strong>0.021</strong></td><td>0.0227</td><td>0.0216</td></tr><tr><td>Pb</td><td>0.057</td><td>0.0119</td><td><strong>0.240</strong></td><td><strong>0.67</strong></td><td><strong>0.040</strong></td><td>0.0336</td><td>0.0316</td></tr><tr><td>Th</td><td>0.0378</td><td>0.0308</td><td><strong>0.038</strong></td><td><strong>0.036</strong></td><td><strong>0.042</strong></td><td>0.0452</td><td>0.034</td></tr><tr><td>U</td><td>0.010</td><td>0.0080</td><td><strong>0.013</strong></td><td><strong>0.009</strong></td><td><strong>0.015</strong></td><td>0.0128</td><td>0.0102</td></tr></tbody></table>

Note: Data for two H chondrites (Ejby, Blaubeuren) and two L chondrites (Braunschweig, Antonin) for comparison. Literature data are from Haack et al. (2019), Bartoschewitz et al. (2017), Bischoff, Patzek, et al. (2022) and Bischoff, Storz, et al. (2022). The data for mean L and H chondrites are taken from Lodders and Fegley Jr. (1998).

## Cosmic Ray Exposure Ages

The production rates of cosmogenic ³He, ²¹Ne, and ³⁸Ar derived from the model for OCs from Leya

and Masarik (2009) and the resulting CRE ages are given in Table 8. The cosmogenic ³He, ²¹Ne, and ³⁸Ar concentrations used to calculate the CRE ages were error-weighted averages of the values for both aliquots. While

<footnote>ªData in wt%, other data in ppm.</footnote>
<table><caption>TABLE 5. Major and trace element abundances of the anomalous (an) Elmshorn H3-6 chondrite breccia (sample E03). The mean of about 1600 randomly obtained microprobe analyses on two Elmshorn samples revealed Al and Si concentrations of 1.38 and 18.6 wt%, respectively.</caption><thead><tr><th>Element</th><th>Ejby H5/6</th><th>Blaubeuren H5-6</th><th>Mean H</th><th>Elmshorn H3-6-an</th><th>Mean L</th><th>Braunschweig L6</th><th>Antonin L4-5</th></tr></thead><tbody><tr><td>Al</td><td>1.10<sup>a</sup></td><td>1.05<sup>a</sup></td><td><strong>1.06<sup>a</sup></strong></td><td></td><td><strong>1.16<sup>a</sup></strong></td><td>1.159<sup>a</sup></td><td>1.01<sup>a</sup></td></tr><tr><td>Fe</td><td>28.7<sup>a</sup></td><td>24.5<sup>a</sup></td><td><strong>27.2<sup>a</sup></strong></td><td><strong>31.7<sup>a</sup></strong></td><td><strong>21.8<sup>a</sup></strong></td><td>21.6<sup>a</sup></td><td>22.0<sup>a</sup></td></tr><tr><td>Mg</td><td>14.99<sup>a</sup></td><td>13.28<sup>a</sup></td><td><strong>14.1<sup>a</sup></strong></td><td><strong>12.6<sup>a</sup></strong></td><td><strong>14.9<sup>a</sup></strong></td><td>15.0<sup>a</sup></td><td>14.4<sup>a</sup></td></tr><tr><td>Na</td><td>0.67<sup>a</sup></td><td>0.25<sup>a</sup></td><td><strong>0.61<sup>a</sup></strong></td><td><strong>0.60<sup>a</sup></strong></td><td><strong>0.69<sup>a</sup></strong></td><td>0.712<sup>a</sup></td><td>0.65<sup>a</sup></td></tr><tr><td>Ni</td><td>2.11<sup>a</sup></td><td>1.57<sup>a</sup></td><td><strong>1.71<sup>a</sup></strong></td><td><strong>2.05<sup>a</sup></strong></td><td><strong>1.24<sup>a</sup></strong></td><td>1.23<sup>a</sup></td><td>1.56<sup>a</sup></td></tr><tr><td>P</td><td>1309</td><td>812</td><td><strong>1200</strong></td><td><strong>1177</strong></td><td><strong>1030</strong></td><td>1310</td><td>905</td></tr><tr><td>K</td><td>950</td><td>421</td><td><strong>780</strong></td><td><strong>997</strong></td><td><strong>920</strong></td><td>1021</td><td>873</td></tr><tr><td>Ca</td><td>1.28<sup>a</sup></td><td>1.02<sup>a</sup></td><td><strong>1.22<sup>a</sup></strong></td><td><strong>1.08<sup>a</sup></strong></td><td><strong>1.33<sup>a</sup></strong></td><td>1.41<sup>a</sup></td><td>1.21<sup>a</sup></td></tr><tr><td>Sc</td><td>8.7</td><td>7.39</td><td><strong>7.8</strong></td><td><strong>4.4</strong></td><td><strong>8.1</strong></td><td>10.01</td><td>8.52</td></tr><tr><td>Ti</td><td>620</td><td>480</td><td><strong>630</strong></td><td><strong>581</strong></td><td><strong>670</strong></td><td>644</td><td>610</td></tr><tr><td>V</td><td>74</td><td>49.4</td><td><strong>73</strong></td><td><strong>73</strong></td><td><strong>75</strong></td><td>70.09</td><td>62.1</td></tr><tr><td>Cr</td><td>3118</td><td>3597</td><td><strong>3500</strong></td><td><strong>3573</strong></td><td><strong>3690</strong></td><td>3804</td><td>3048</td></tr><tr><td>Mn</td><td>2606</td><td>2036</td><td><strong>2340</strong></td><td><strong>2417</strong></td><td><strong>2590</strong></td><td>0.267<sup>a</sup></td><td>2478</td></tr><tr><td>Co</td><td>715</td><td>621</td><td><strong>830</strong></td><td><strong>1105</strong></td><td><strong>580</strong></td><td>601</td><td>582</td></tr><tr><td>Cu</td><td>73.1</td><td></td><td></td><td><strong>84</strong></td><td><strong>90</strong></td><td></td><td>84.6</td></tr><tr><td>Zn</td><td>43.5</td><td>25.6</td><td><strong>47</strong></td><td><strong>57</strong></td><td><strong>57</strong></td><td>43.96</td><td>42.4</td></tr><tr><td>Ga</td><td>5.06</td><td>4.46</td><td><strong>6.0</strong></td><td><strong>5.8</strong></td><td><strong>5.4</strong></td><td>5.05</td><td>4.81</td></tr><tr><td>Rb</td><td>2.88</td><td>1.17</td><td><strong>2.3</strong></td><td><strong>5.8</strong></td><td><strong>2.8</strong></td><td>3.06</td><td>2.59</td></tr><tr><td>Sr</td><td>10.9</td><td>5.58</td><td><strong>8.8</strong></td><td><strong>9.4</strong></td><td><strong>11</strong></td><td>11.34</td><td>10.5</td></tr><tr><td>Y</td><td>2.97</td><td>1.65</td><td><strong>2.0</strong></td><td><strong>2.1</strong></td><td><strong>1.8</strong></td><td>2.32</td><td>1.98</td></tr><tr><td>Zr</td><td>4.63</td><td>4.47</td><td><strong>7.3</strong></td><td><strong>4.8</strong></td><td><strong>6.4</strong></td><td>6.48</td><td>5.02</td></tr><tr><td>Nb</td><td>0.381</td><td>0.399</td><td><strong>0.4</strong></td><td><strong>0.59</strong></td><td><strong>0.4</strong></td><td>0.46</td><td>0.43</td></tr><tr><td>Cs</td><td>0.0178</td><td></td><td></td><td><strong>0.32</strong></td><td></td><td>0.048</td><td>0.030</td></tr><tr><td>Ba</td><td>3.49</td><td>2.06</td><td><strong>4.4</strong></td><td><strong>2.90</strong></td><td><strong>4.1</strong></td><td>3.78</td><td>3.53</td></tr><tr><td>La</td><td>0.344</td><td>0.226</td><td><strong>0.301</strong></td><td><strong>0.295</strong></td><td><strong>0.318</strong></td><td>0.328</td><td>0.277</td></tr><tr><td>Ce</td><td>0.885</td><td>0.599</td><td><strong>0.763</strong></td><td><strong>0.777</strong></td><td><strong>0.970</strong></td><td>0.873</td><td>0.711</td></tr><tr><td>Pr</td><td>0.132</td><td>0.089</td><td><strong>0.120</strong></td><td><strong>0.116</strong></td><td><strong>0.140</strong></td><td>0.128</td><td>0.107</td></tr><tr><td>Nd</td><td>0.658</td><td>0.450</td><td><strong>0.581</strong></td><td><strong>0.593</strong></td><td><strong>0.700</strong></td><td>0.649</td><td>0.538</td></tr><tr><td>Sm</td><td>0.211</td><td>0.147</td><td><strong>0.194</strong></td><td><strong>0.188</strong></td><td><strong>0.303</strong></td><td>0.218</td><td>0.176</td></tr><tr><td>Eu</td><td>0.072</td><td>0.064</td><td><strong>0.074</strong></td><td><strong>0.069</strong></td><td><strong>0.080</strong></td><td>0.0827</td><td>0.079</td></tr><tr><td>Gd</td><td>0.303</td><td>0.204</td><td><strong>0.275</strong></td><td><strong>0.266</strong></td><td><strong>0.317</strong></td><td>0.30</td><td>0.243</td></tr><tr><td>Tb</td><td>0.0548</td><td>0.0348</td><td><strong>0.049</strong></td><td><strong>0.048</strong></td><td><strong>0.059</strong></td><td>0.0549</td><td>0.045</td></tr><tr><td>Dy</td><td>0.369</td><td>0.262</td><td><strong>0.305</strong></td><td><strong>0.330</strong></td><td><strong>0.372</strong></td><td>0.378</td><td>0.306</td></tr><tr><td>Ho</td><td>0.0815</td><td>0.0586</td><td><strong>0.074</strong></td><td><strong>0.073</strong></td><td><strong>0.089</strong></td><td>0.0835</td><td>0.069</td></tr><tr><td>Er</td><td>0.239</td><td>0.174</td><td><strong>0.213</strong></td><td><strong>0.216</strong></td><td><strong>0.252</strong></td><td>0.250</td><td>0.302</td></tr><tr><td>Tm</td><td>0.0356</td><td>0.0270</td><td><strong>0.033</strong></td><td></td><td><strong>0.038</strong></td><td></td><td>0.031</td></tr><tr><td>Yb</td><td>0.228</td><td>0.178</td><td><strong>0.203</strong></td><td><strong>0.212</strong></td><td><strong>0.226</strong></td><td>0.256</td><td>0.206</td></tr><tr><td>Lu</td><td>0.0345</td><td>0.0274</td><td><strong>0.033</strong></td><td><strong>0.031</strong></td><td><strong>0.034</strong></td><td>0.0392</td><td>0.0313</td></tr><tr><td>Hf</td><td>0.135</td><td>0.135</td><td><strong>0.150</strong></td><td><strong>0.135</strong></td><td><strong>0.170</strong></td><td>0.197</td><td>0.152</td></tr><tr><td>Ta</td><td>0.0107</td><td>0.0163</td><td><strong>0.021</strong></td><td><strong>0.018</strong></td><td><strong>0.021</strong></td><td>0.0227</td><td>0.0216</td></tr><tr><td>Pb</td><td>0.057</td><td>0.0119</td><td><strong>0.240</strong></td><td><strong>0.67</strong></td><td><strong>0.040</strong></td><td>0.0336</td><td>0.0316</td></tr><tr><td>Th</td><td>0.0378</td><td>0.0308</td><td><strong>0.038</strong></td><td><strong>0.036</strong></td><td><strong>0.042</strong></td><td>0.0452</td><td>0.034</td></tr><tr><td>U</td><td>0.010</td><td>0.0080</td><td><strong>0.013</strong></td><td><strong>0.009</strong></td><td><strong>0.015</strong></td><td>0.0128</td><td>0.0102</td></tr></tbody></table>

Note: Data for two H chondrites (Ejby, Blaubeuren) and two L chondrites (Braunschweig, Antonin) for comparison. Literature data are from Haack et al. (2019), Bartoschewitz et al. (2017), Bischoff, Patzek, et al. (2022) and Bischoff, Storz, et al. (2022). The data for mean L and H chondrites are taken from Lodders and Fegley Jr. (1998).

## Cosmic Ray Exposure Ages

The production rates of cosmogenic ³He, ²¹Ne, and ³⁸Ar derived from the model for OCs from Leya

and Masarik (2009) and the resulting CRE ages are given in Table 8. The cosmogenic ³He, ²¹Ne, and ³⁸Ar concentrations used to calculate the CRE ages were error-weighted averages of the values for both aliquots. While

<footnote>ªData in wt%, other data in ppm.</footnote>
<table><caption>TABLE 6. Nucleosynthetic Ti and Cr isotope data of Elmshorn.</caption><thead><tr><th>Sample</th><th>n (Ti)<sup>a</sup></th><th>ε<sup>46</sup>Ti</th><th>2 SE<sup>b</sup></th><th>ε<sup>48</sup>Ti</th><th>2 SE<sup>b</sup></th><th>ε<sup>50</sup>Ti</th><th>2 SE<sup>b</sup></th><th>n(Cr)<sup>a</sup></th><th>ε<sup>53</sup>Cr</th><th>2 SE<sup>b</sup></th><th>ε<sup>54</sup>Cr</th><th>2 SE<sup>b</sup></th></tr></thead><tbody><tr><td>Elmshorn</td><td>10</td><td>-0.09</td><td>0.09</td><td>-0.02</td><td>0.05</td><td>-0.53</td><td>0.06</td><td>6</td><td>0.23</td><td>0.10</td><td>-0.30</td><td>0.15</td></tr><tr><td>Forest Vale<sup>c</sup></td><td>9</td><td>-0.16</td><td>0.05</td><td>-0.06</td><td>0.03</td><td>-0.57</td><td>0.07</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>BHVO-2</td><td>8</td><td>0.00</td><td>0.09</td><td>0.01</td><td>0.04</td><td>0.06</td><td>0.05</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>DTS-2</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>8</td><td>0.03</td><td>0.05</td><td>0.06</td><td>0.10</td></tr></tbody></table>

the ²¹Ne_cos (T₂₁) and ³⁸Ar_cos (T₃₈) ages overlap within their ranges, the ³He_cos (T₃) age is significantly shorter. The lower age could be explained by a ³He loss due to heating (e.g., during atmospheric entry), which preferentially affects the lighter noble gases. Comparing the (³He/²¹Ne)cos and (²²Ne/²¹Ne)cos ratios for Elmshorn 1 and 2 with the study from Nishiizumi et al. (1980), however, does not show a sufficiently large ³He loss. Alternatively, or additionally, it could also result from an overestimation of the ³He production rate in the Leya model. Dalcher et al. (2013) compared the (³He/²¹Ne)cos and (²²Ne/²¹Ne)cos predicted by the Leya model with data collected from 138 chondrites in Nishiizumi et al. (1980), and the study showed systematically higher ³He_cos values for the Leya model. An overestimated production rate would mean that less time would have been needed to produce our measured ³He_cos, leading to an underestimation of the CRE age. The difference in (³He/²¹Ne)cos between the average trends suggested by the observed and model data (see figure 1 from Dalcher et al., 2013) at (²²Ne/²¹Ne)cos ~ 1.111 (measured for Elmshorn) would be about 15%, as estimated from the averaged lines. This suggests that perhaps both the overestimated production rate and some loss of ³He_cos could have contributed to the low T₃. Our preferred CRE age for Elmshorn is ~17–20 Myr.

## Further Constraints on Preatmospheric Radius and Shielding Depths by Cosmogenic Radionuclides

The IAMS determined nuclide ratios, which can be explained by long CRE ages (resulting in saturation of the respective radionuclide), that is, around 10⁻¹⁰ and 10⁻¹² for ²⁶Al/²⁷Al and ⁴¹Ca/⁴⁰Ca (Table 9), respectively. Associated machine blanks were 3–4 orders of magnitude lower, hence, no blank correction was applied to the results. Due to missing uncertainties for the used stable Al and Ca concentrations, no further uncertainty was added to specific activities. As IAMS samples (containing only about 1% Al and Ca each) are generally resulting in lower stable nuclide currents than those from chemically processed Al₂O₃ and CaF₂ samples (1%–2%), the counting statistics show low results.

The ²⁶Al value from IAMS (originating from a 0.6 g aliquot of E03) is in reasonable (2-sigma) agreement with the ²⁶Al value from gamma spectrometry (originating from the 233.5 g large E02), which can be well-explained by the inhomogeneous and thus perhaps different chemical compositions, that is, target element concentrations for production of ²⁶Al, in the two specimens. The IAMS ²⁶Al value agrees within 1-sigma with the ²⁶Al gamma spectrometric value of E01, not only due to the much higher relative uncertainty of E01 compared to E02. The comparison (Figure 14) of the experimental ²⁶Al and ⁴¹Ca with radius- and depth-dependent (saturation) production rate calculations (Leya & Masarik, 2009) let us further constrain the radius to 20–40 cm and a near-surface sample origin of E03 in the meteoroid. Both nuclide concentrations clearly exclude larger radii, hence, confirming the determination of a radius between 25 and 50 cm and low shielding of 6–10 cm based on the noble gas data and ablation considerations above. Updated Monte Carlo-calculated production rates, especially for ⁴¹Ca would be highly appreciated, but are not yet at our disposal. A more recent value for the half-life of ⁴¹Ca (Jörg et al., 2012) and the need for renormalization of underlying thin- and thick-target cross-section measurements to at-that-time used ⁴¹Ca/Ca standards (Geppert et al., 2005) should increase the accuracy of the calculated production rates resulting in better size and shielding information for meteorite samples.

The gamma-measured specific activity of ²²Na of Elmshorn (E02) compared to radius- and depth-dependent (saturation) production rate calculations for ²²Na (Leya et al., 2021, Figure S7) can be explained by a preatmospheric rather near-surface exposure within a body of smaller radii (>12.5 cm), too. However, the measured ²²Na alone is generally compatible with radii up to 80 cm.

## U/Th-He and K-Ar Gas Retention Ages

The U/Th-He (T₄) and K-Ar (T₄₀) chronometers for both Elmshorn 1 and 2 yield comparable gas retention ages (Table 10). The similarity in both systems - although

<footnote><sup>a</sup>Number of measurements.</footnote>

<footnote><sup>b</sup>Isotopic values are averages of repeats. Uncertainties are given in 2 SE (SE = SD/√n).</footnote>

<footnote><sup>c</sup>Titanium analysis by Williams (2015), remeasured in this study.</footnote>
<table><caption>TABLE 6. Nucleosynthetic Ti and Cr isotope data of Elmshorn.</caption><thead><tr><th>Sample</th><th>n (Ti)<sup>a</sup></th><th>ε<sup>46</sup>Ti</th><th>2 SE<sup>b</sup></th><th>ε<sup>48</sup>Ti</th><th>2 SE<sup>b</sup></th><th>ε<sup>50</sup>Ti</th><th>2 SE<sup>b</sup></th><th>n(Cr)<sup>a</sup></th><th>ε<sup>53</sup>Cr</th><th>2 SE<sup>b</sup></th><th>ε<sup>54</sup>Cr</th><th>2 SE<sup>b</sup></th></tr></thead><tbody><tr><td>Elmshorn</td><td>10</td><td>-0.09</td><td>0.09</td><td>-0.02</td><td>0.05</td><td>-0.53</td><td>0.06</td><td>6</td><td>0.23</td><td>0.10</td><td>-0.30</td><td>0.15</td></tr><tr><td>Forest Vale<sup>c</sup></td><td>9</td><td>-0.16</td><td>0.05</td><td>-0.06</td><td>0.03</td><td>-0.57</td><td>0.07</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>BHVO-2</td><td>8</td><td>0.00</td><td>0.09</td><td>0.01</td><td>0.04</td><td>0.06</td><td>0.05</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>DTS-2</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>8</td><td>0.03</td><td>0.05</td><td>0.06</td><td>0.10</td></tr></tbody></table>

the $^{21}$Ne$_{cos}$ (T$_{21}$) and $^{38}$Ar$_{cos}$ (T$_{38}$) ages overlap within their ranges, the $^{3}$He$_{cos}$ (T$_{3}$) age is significantly shorter. The lower age could be explained by a $^{3}$He loss due to heating (e.g., during atmospheric entry), which preferentially affects the lighter noble gases. Comparing the ($^{3}$He/$^{21}$Ne)$_{cos}$ and ($^{22}$Ne/$^{21}$Ne)$_{cos}$ ratios for Elmshorn 1 and 2 with the study from Nishiizumi et al. (1980), however, does not show a sufficiently large $^{3}$He loss. Alternatively, or additionally, it could also result from an overestimation of the $^{3}$He production rate in the Leya model. Dalcher et al. (2013) compared the ($^{3}$He/$^{21}$Ne)$_{cos}$ and ($^{22}$Ne/$^{21}$Ne)$_{cos}$ predicted by the Leya model with data collected from 138 chondrites in Nishiizumi et al. (1980), and the study showed systematically higher $^{3}$He$_{cos}$ values for the Leya model. An overestimated production rate would mean that less time would have been needed to produce our measured $^{3}$He$_{cos}$, leading to an underestimation of the CRE age. The difference in ($^{3}$He/$^{21}$Ne)$_{cos}$ between the average trends suggested by the observed and model data (see figure 1 from Dalcher et al., 2013) at ($^{22}$Ne/$^{21}$Ne)$_{cos}$ ~ 1.111 (measured for Elmshorn) would be about 15%, as estimated from the averaged lines. This suggests that perhaps both the overestimated production rate and some loss of $^{3}$He$_{cos}$ could have contributed to the low T$_{3}$. Our preferred CRE age for Elmshorn is ~17–20 Myr.

## Further Constraints on Preatmospheric Radius and Shielding Depths by Cosmogenic Radionuclides

The IAMS determined nuclide ratios, which can be explained by long CRE ages (resulting in saturation of the respective radionuclide), that is, around $10^{-10}$ and $10^{-12}$ for $^{26}$Al/$^{27}$Al and $^{41}$Ca/$^{40}$Ca (Table 9), respectively. Associated machine blanks were 3–4 orders of magnitude lower, hence, no blank correction was applied to the results. Due to missing uncertainties for the used stable Al and Ca concentrations, no further uncertainty was added to specific activities. As IAMS samples (containing only about 1% Al and Ca each) are generally resulting in lower stable nuclide currents than those from chemically processed Al$_{2}$O$_{3}$ and CaF$_{2}$ samples (1%–2%), the counting statistics show low results.

The $^{26}$Al value from IAMS (originating from a 0.6 g aliquot of E03) is in reasonable (2-sigma) agreement with the $^{26}$Al value from gamma spectrometry (originating from the 233.5 g large E02), which can be well-explained by the inhomogeneous and thus perhaps different chemical compositions, that is, target element concentrations for production of $^{26}$Al, in the two specimens. The IAMS $^{26}$Al value agrees within 1-sigma with the $^{26}$Al gamma spectrometric value of E01, not only due to the much higher relative uncertainty of E01 compared to E02. The comparison (Figure 14) of the experimental $^{26}$Al and $^{41}$Ca with radius- and depth-dependent (saturation) production rate calculations (Leya & Masarik, 2009) let us further constrain the radius to 20–40 cm and a near-surface sample origin of E03 in the meteoroid. Both nuclide concentrations clearly exclude larger radii, hence, confirming the determination of a radius between 25 and 50 cm and low shielding of 6–10 cm based on the noble gas data and ablation considerations above. Updated Monte Carlo-calculated production rates, especially for $^{41}$Ca would be highly appreciated, but are not yet at our disposal. A more recent value for the half-life of $^{41}$Ca (Jörg et al., 2012) and the need for renormalization of underlying thin- and thick-target cross-section measurements to at-that-time used $^{41}$Ca/Ca standards (Geppert et al., 2005) should increase the accuracy of the calculated production rates resulting in better size and shielding information for meteorite samples.

The gamma-measured specific activity of $^{22}$Na of Elmshorn (E02) compared to radius- and depth-dependent (saturation) production rate calculations for $^{22}$Na (Leya et al., 2021, Figure S7) can be explained by a preatmospheric rather near-surface exposure within a body of smaller radii (>12.5 cm), too. However, the measured $^{22}$Na alone is generally compatible with radii up to 80 cm.

## U/Th-He and K-Ar Gas Retention Ages

The U/Th-He ($T_{4}$) and K-Ar ($T_{40}$) chronometers for both Elmshorn 1 and 2 yield comparable gas retention ages (Table 10). The similarity in both systems - although

<footnote><sup>a</sup>Number of measurements.</footnote>

<footnote><sup>b</sup>Isotopic values are averages of repeats. Uncertainties are given in 2 SE (SE = SD/√n).</footnote>

<footnote><sup>c</sup>Titanium analysis by Williams (2015), remeasured in this study.</footnote>
<table><caption>TABLE 7. Noble gas concentrations and isotope ratios in Elmshorn (sample E03).</caption><thead><tr><th colspan="2">(a) Helium and Ne concentrations (in 10<sup>-8</sup> cm<sup>3</sup> STP g<sup>-1</sup>) and isotopic ratios</th><th rowspan="2">20<sup>Ne</sup></th><th rowspan="2">20<sup>Ne</sup>/22<sup>Ne</sup></th><th rowspan="2">21<sup>Ne</sup>/22<sup>Ne</sup></th><th rowspan="2">22<sup>Ne</sup>/21<sup>Ne</sup></th></tr><tr><th>Sample</th><th>Mass (mg)</th></tr></thead><tbody><tr><td>Elmshorn 1</td><td>15.307 ± 0.023</td><td>882.4 ± 3.1</td><td>214.2 ± 2.3</td><td>5.095 ± 0.027</td><td>0.8644 ± 0.0035</td><td>0.9035 ± 0.0040</td><td>1.1068 ± 0.0049</td></tr><tr><td>Elmshorn 2</td><td>15.090 ± 0.026</td><td>888.1 ± 3.3</td><td>210.8 ± 1.2</td><td>5.190 ± 0.037</td><td>0.8704 ± 0.0048</td><td>0.8950 ± 0.0047</td><td>1.1173 ± 0.0058</td></tr><tr><td>Mean</td><td></td><td></td><td></td><td></td><td></td><td>0.8999 ± 0.0030</td><td>1.1112 ± 0.0038</td></tr></tbody></table><table><thead><tr><th colspan="2">(b) Argon (in 10<sup>-8</sup> cm<sup>3</sup> STP g<sup>-1</sup>) and Kr (in 10<sup>-10</sup> cm<sup>3</sup> STP g<sup>-1</sup>) concentrations and isotopic ratios</th><th rowspan="2">80<sup>Kr</sup>/84<sup>Kr</sup></th><th rowspan="2">82<sup>Kr</sup>/84<sup>Kr</sup></th><th rowspan="2">83<sup>Kr</sup>/84<sup>Kr</sup></th><th rowspan="2">86<sup>Kr</sup>/84<sup>Kr</sup></th></tr><tr><th>Sample</th><th>36<sup>Ar</sup></th><th>36<sup>Ar</sup>/38<sup>Ar</sup></th><th>40<sup>Ar</sup>/36<sup>Ar</sup></th><th>84<sup>Kr</sup></th><th>84<sup>Kr</sup>=100</th></tr></thead><tbody><tr><td>Elmshorn 1</td><td>7.716 ± 0.050</td><td>3.498 ± 0.022</td><td>440.8 ± 4.3</td><td>7.414 ± 0.029</td><td>0.665 ± 0.029</td><td>4.349 ± 0.070</td><td>20.71 ± 0.18</td><td>20.48 ± 0.15</td><td>31.17 ± 0.28</td></tr><tr><td>Elmshorn 2</td><td>7.439 ± 0.038</td><td>3.458 ± 0.017</td><td>441.2 ± 4.1</td><td>7.235 ± 0.033</td><td>0.631 ± 0.039</td><td>4.345 ± 0.082</td><td>20.74 ± 0.17</td><td>20.91 ± 0.40</td><td>30.42 ± 0.30</td></tr></tbody></table><table><thead><tr><th colspan="2">(c) Xenon concentrations (in 10<sup>-10</sup> cm<sup>3</sup> STP g<sup>-1</sup>) and isotopic ratios</th><th rowspan="2">128<sup>Xe</sup>/132<sup>Xe</sup></th><th rowspan="2">129<sup>Xe</sup>/132<sup>Xe</sup></th><th rowspan="2">130<sup>Xe</sup>/132<sup>Xe</sup></th><th rowspan="2">131<sup>Xe</sup>/132<sup>Xe</sup></th><th rowspan="2">134<sup>Xe</sup>/132<sup>Xe</sup></th><th rowspan="2">136<sup>Xe</sup>/132<sup>Xe</sup></th></tr><tr><th>Sample</th><th>132<sup>Xe</sup></th><th>132<sup>Xe</sup>/132<sup>Xe</sup></th><th>132<sup>Xe</sup>/132<sup>Xe</sup></th><th>132<sup>Xe</sup>/132<sup>Xe</sup></th></tr></thead><tbody><tr><td>Elmshorn 1</td><td>10.991 ± 0.048</td><td>0.481 ± 0.016</td><td>0.4039 ± 0.0044</td><td>8.191 ± 0.074</td><td>160.66 ± 0.91</td><td>16.77 ± 0.18</td><td>82.40 ± 0.52</td><td>38.10 ± 0.37</td><td>32.23 ± 0.33</td></tr><tr><td>Elmshorn 2</td><td>10.205 ± 0.058</td><td>0.519 ± 0.026</td><td>0.402 ± 0.017</td><td>8.227 ± 0.064</td><td>158.35 ± 0.97</td><td>16.18 ± 0.16</td><td>80.89 ± 0.56</td><td>37.20 ± 0.31</td><td>30.91 ± 0.29</td></tr></tbody></table>
<table><caption>TABLE 7. Noble gas concentrations and isotope ratios in Elmshorn (sample E03).</caption><thead><tr><th colspan="2">(a) Helium and Ne concentrations (in 10<sup>-8</sup> cm<sup>3</sup> STP g<sup>-1</sup>) and isotopic ratios</th><th></th><th></th><th></th><th></th><th></th><th></th></tr><tr><th>Sample</th><th>Mass (mg)</th><th><sup>4</sup>He</th><th><sup>3</sup>He/<sup>4</sup>He × 10<sup>4</sup></th><th><sup>20</sup>Ne</th><th><sup>20</sup>Ne/<sup>22</sup>Ne</th><th><sup>21</sup>Ne/<sup>22</sup>Ne</th><th><sup>22</sup>Ne/<sup>21</sup>Ne</th></tr></thead><tbody><tr><td>Elmshorn 1</td><td>15.307 ± 0.023</td><td>882.4 ± 3.1</td><td>214.2 ± 2.3</td><td>5.095 ± 0.027</td><td>0.8644 ± 0.0035</td><td>0.9035 ± 0.0040</td><td>1.1068 ± 0.0049</td></tr><tr><td>Elmshorn 2</td><td>15.090 ± 0.026</td><td>888.1 ± 3.3</td><td>210.8 ± 1.2</td><td>5.190 ± 0.037</td><td>0.8704 ± 0.0048</td><td>0.8950 ± 0.0047</td><td>1.1173 ± 0.0058</td></tr><tr><td>Mean</td><td></td><td></td><td></td><td></td><td></td><td>0.8999 ± 0.0030</td><td>1.1112 ± 0.0038</td></tr><tr><th colspan="2">(b) Argon (in 10<sup>-8</sup> cm<sup>3</sup> STP g<sup>-1</sup>) and Kr (in 10<sup>-10</sup> cm<sup>3</sup> STP g<sup>-1</sup>) concentrations and isotopic ratios</th><th><sup>36</sup>Ar</th><th><sup>36</sup>Ar/<sup>38</sup>Ar</th><th><sup>40</sup>Ar/<sup>36</sup>Ar</th><th><sup>84</sup>Kr</th><th><sup>80</sup>Kr/<sup>84</sup>Kr</th><th><sup>82</sup>Kr/<sup>84</sup>Kr</th><th><sup>83</sup>Kr/<sup>84</sup>Kr</th><th><sup>86</sup>Kr/<sup>84</sup>Kr</th></tr><tr><td>Elmshorn 1</td><td>7.716 ± 0.050</td><td>3.498 ± 0.022</td><td>440.8 ± 4.3</td><td>7.414 ± 0.029</td><td>0.665 ± 0.029</td><td>4.349 ± 0.070</td><td>20.71 ± 0.18</td><td>20.48 ± 0.15</td><td>31.17 ± 0.28</td></tr><tr><td>Elmshorn 2</td><td>7.439 ± 0.038</td><td>3.458 ± 0.017</td><td>441.2 ± 4.1</td><td>7.235 ± 0.033</td><td>0.631 ± 0.039</td><td>4.345 ± 0.082</td><td>20.74 ± 0.17</td><td>20.91 ± 0.40</td><td>30.42 ± 0.30</td></tr><tr><th colspan="2">(c) Xenon concentrations (in 10<sup>-10</sup> cm<sup>3</sup> STP g<sup>-1</sup>) and isotopic ratios</th><th><sup>124</sup>Xe/<sup>132</sup>Xe</th><th><sup>126</sup>Xe/<sup>132</sup>Xe</th><th><sup>128</sup>Xe/<sup>132</sup>Xe</th><th><sup>129</sup>Xe/<sup>132</sup>Xe</th><th><sup>130</sup>Xe/<sup>132</sup>Xe</th><th><sup>131</sup>Xe/<sup>132</sup>Xe</th><th><sup>134</sup>Xe/<sup>132</sup>Xe</th><th><sup>136</sup>Xe/<sup>132</sup>Xe</th></tr><tr><td>Elmshorn 1</td><td>10.991 ± 0.048</td><td>0.481 ± 0.016</td><td>0.4039 ± 0.0044</td><td>8.191 ± 0.074</td><td>160.66 ± 0.91</td><td>16.77 ± 0.18</td><td>82.40 ± 0.52</td><td>38.10 ± 0.37</td><td>32.23 ± 0.33</td></tr><tr><td>Elmshorn 2</td><td>10.205 ± 0.058</td><td>0.519 ± 0.026</td><td>0.402 ± 0.017</td><td>8.227 ± 0.064</td><td>158.35 ± 0.97</td><td>16.18 ± 0.16</td><td>80.89 ± 0.56</td><td>37.20 ± 0.31</td><td>30.91 ± 0.29</td></tr></tbody></table>
<table><caption>TABLE 8. Suitable shielding conditions matching our measured ($^{22}$Ne/$^{21}$Ne)cos value, determined with the model by Leya and Masarik (2009) for H chondrite meteoroids adapted to Elmshorn sample E03, cosmogenic $^{3}$He, $^{21}$Ne, and $^{38}$Ar isotope concentrations (in $10^{-8}$ cm$^3$ STP g$^{-1}$), production rates $P_x$ (in $10^{-8}$ cm$^3$/[g × Myr]) and CRE ages $T_x$ (Myr).</caption><thead><tr><th>Sample</th><th>Preatmospheric radius (cm)<sup>a</sup></th><th>Sample depth within meteoroid (cm)</th><th><sup>3</sup>He<sub>cos</sub></th><th><sup>21</sup>Ne<sub>cos</sub></th><th><sup>38</sup>Ar<sub>cos</sub></th></tr></thead><tbody><tr><td>Elmshorn 1</td><td rowspan="3">25–50</td><td rowspan="3">6–10</td><td>18.90 ± 0.19</td><td>5.325 ± 0.029</td><td>0.863 ± 0.021</td></tr><tr><td>Elmshorn 2</td><td>18.721 ± 0.086</td><td>5.337 ± 0.037</td><td>0.860 ± 0.017</td></tr><tr><td>Mean</td><td>18.752 ± 0.079</td><td>5.330 ± 0.023</td><td>0.861 ± 0.013</td></tr></tbody></table><table><thead><tr><th>Sample</th><th>P<sub>3</sub></th><th>P<sub>21</sub></th><th>P<sub>38</sub></th><th>T<sub>3</sub></th><th>T<sub>21</sub></th><th>T<sub>38</sub></th><th>Preferred age</th></tr></thead><tbody><tr><td>Elmshorn 1</td><td rowspan="3">1.63–1.72</td><td rowspan="3">0.30–0.32</td><td rowspan="3">0.044–0.047</td><td rowspan="3">~11–12</td><td rowspan="3">~17–18</td><td rowspan="3">~18–20</td><td rowspan="3">~17–20</td></tr><tr><td>Elmshorn 2</td></tr><tr><td>Mean</td></tr></tbody></table>

<table><caption>TABLE 9. Nuclide ratios measured by IAMS and resulting specific radionuclide activities in Elmshorn.</caption><thead><tr><th></th><th><sup>26</sup>Al/<sup>27</sup>Al</th><th><sup>26</sup>Al (dpm kg<sup>-1</sup>)</th><th><sup>41</sup>Ca/<sup>40</sup>Ca</th><th><sup>41</sup>Ca (dpm kg<sup>-1</sup>)</th></tr></thead><tbody><tr><td>Elmshorn</td><td>(1.110 ± 0.036) × 10<sup>-10</sup></td><td>52.4 ± 1.7</td><td>(4.90 ± 0.72) × 10<sup>-12</sup></td><td>9.8 ± 1.4</td></tr><tr><td>Blank</td><td>(6.4 ± 2.4) × 10<sup>-14</sup></td><td></td><td>(2.8 ± 2.8) × 10<sup>-15</sup></td><td></td></tr></tbody></table>

<table><caption>TABLE 10. Radiogenic $^{4}$He and $^{40}$Ar concentrations (in $10^{-8}$ cm$^3$ STP g$^{-1}$), K concentrations (ppm), U and Th concentrations (ppb) measured on the ICP-SFMS (Table 5), and U/Th-He and K-Ar chronometer-derived gas retention ages $T_x$ (Gyr).</caption><thead><tr><th>Sample</th><th><sup>4</sup>He<sub>rad</sub></th><th><sup>40</sup>Ar<sub>rad</sub></th><th>K</th><th>U</th><th>Th</th><th>T<sub>4</sub></th><th>T<sub>40</sub></th></tr></thead><tbody><tr><td>Elmshorn 1</td><td>775.6 ± 9.1</td><td>2343 ± 18</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Elmshorn 2</td><td>782.4 ± 9.0</td><td>2265 ± 15</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Average</td><td>779 ± 12</td><td>2306 ± 56</td><td>997</td><td>9</td><td>36</td><td>2.88–2.95</td><td>2.60–2.67</td></tr></tbody></table>

He is more volatile than Ar - suggests that no major resetting events occurred since ~2.8 Gyr. The age recorded could potentially represent the closure time after the catastrophic collision between H and L chondrite parent bodies and re-accretion of Elmshorn's parent body. The only slightly higher $T_4$ age (2.88–2.95 Gyr) relative to the $T_{40}$ age (2.60–2.67 Gyr) could be due to chemical heterogeneities within Elmshorn. For example, assuming a deviation of ±10% of the measured U, Th, and K concentrations would lead to an overlap between the $T_4$ (2.68–3.19 Gyr) and $T_{40}$ (2.47–2.82 Gyr) ages.

## Further Short- and Long-Lived Radionuclides by Gamma Spectrometry

For Elmshorn samples E01 and E02, the gamma lines were detected from members of the natural decay series of the primordial nuclides $^{238}$U and $^{232}$Th as well as of $^{40}$K

(Table 11) and short-lived cosmogenic nuclides. A total number of 12 cosmogenic radionuclides were detected above the decision thresholds of the method. Their half-lives range from 5.6 days ($^{52}$Mn) up to 705,000 years ($^{26}$Al).

The radionuclide data (Table 11) do not allow any statement about possible disequilibria in the decay series. However, assuming an equilibrium state of the decay series, the terrestrial isotope ratios, and a homogenous distribution in each sample, the U, Th, and K concentrations of the sample E01 would be 18.5 ± 2.2 ng g$^{-1}$, 42 ± 4 ng g$^{-1}$, and 910 ± 120 µg g$^{-1}$, respectively. For sample E02, U, Th, and K concentrations of 11.4 ± 1.3 ng g$^{-1}$, 47 ± 4 ng g$^{-1}$, and 750 ± 60 µg g$^{-1}$, respectively, were calculated. The values of both samples slightly differ from each other and compared with bulk compositional data obtained from Elmshorn fragment E03 (Table 5) showing the heterogeneity of the entire body.

<footnote><sup>a</sup>See text for constraint of upper limit.</footnote>
<table><caption>TABLE 8. Suitable shielding conditions matching our measured ($^{22}$Ne/$^{21}$Ne)cos value, determined with the model by Leya and Masarik (2009) for H chondrite meteoroids adapted to Elmshorn sample E03, cosmogenic $^{3}$He, $^{21}$Ne, and $^{38}$Ar isotope concentrations (in $10^{-8}$ cm$^3$ STP g$^{-1}$), production rates $P_x$ (in $10^{-8}$ cm$^3$/[g × Myr]) and CRE ages $T_x$ (Myr).</caption><thead><tr><th>Sample</th><th>Preatmospheric radius (cm)<sup>a</sup></th><th>Sample depth within meteoroid (cm)</th><th><sup>3</sup>He<sub>cos</sub></th><th><sup>21</sup>Ne<sub>cos</sub></th><th><sup>38</sup>Ar<sub>cos</sub></th></tr></thead><tbody><tr><td>Elmshorn 1</td><td rowspan="3">25–50</td><td rowspan="3">6–10</td><td>18.90 ± 0.19</td><td>5.325 ± 0.029</td><td>0.863 ± 0.021</td></tr><tr><td>Elmshorn 2</td><td>18.721 ± 0.086</td><td>5.337 ± 0.037</td><td>0.860 ± 0.017</td></tr><tr><td>Mean</td><td>18.752 ± 0.079</td><td>5.330 ± 0.023</td><td>0.861 ± 0.013</td></tr><tr><th>Sample</th><th>P<sub>3</sub></th><th>P<sub>21</sub></th><th>P<sub>38</sub></th><th>T<sub>3</sub></th><th>T<sub>21</sub></th><th>T<sub>38</sub></th><th>Preferred age</th></tr><tr><td>Elmshorn 1</td><td rowspan="3">1.63–1.72</td><td rowspan="3">0.30–0.32</td><td rowspan="3">0.044–0.047</td><td rowspan="3">~11–12</td><td rowspan="3">~17–18</td><td rowspan="3">~18–20</td><td rowspan="3">~17–20</td></tr><tr><td>Elmshorn 2</td></tr><tr><td>Mean</td></tr></tbody></table>

<table><caption>TABLE 9. Nuclide ratios measured by IAMS and resulting specific radionuclide activities in Elmshorn.</caption><thead><tr><th></th><th><sup>26</sup>Al/<sup>27</sup>Al</th><th><sup>26</sup>Al (dpm kg<sup>-1</sup>)</th><th><sup>41</sup>Ca/<sup>40</sup>Ca</th><th><sup>41</sup>Ca (dpm kg<sup>-1</sup>)</th></tr></thead><tbody><tr><td>Elmshorn</td><td>(1.110 ± 0.036) × 10<sup>-10</sup></td><td>52.4 ± 1.7</td><td>(4.90 ± 0.72) × 10<sup>-12</sup></td><td>9.8 ± 1.4</td></tr><tr><td>Blank</td><td>(6.4 ± 2.4) × 10<sup>-14</sup></td><td></td><td>(2.8 ± 2.8) × 10<sup>-15</sup></td><td></td></tr></tbody></table>

<table><caption>TABLE 10. Radiogenic $^{4}$He and $^{40}$Ar concentrations (in $10^{-8}$ cm$^3$ STP g$^{-1}$), K concentrations (ppm), U and Th concentrations (ppb) measured on the ICP-SFMS (Table 5), and U/Th-He and K-Ar chronometer-derived gas retention ages $T_x$ (Gyr).</caption><thead><tr><th>Sample</th><th><sup>4</sup>He<sub>rad</sub></th><th><sup>40</sup>Ar<sub>rad</sub></th><th>K</th><th>U</th><th>Th</th><th>T<sub>4</sub></th><th>T<sub>40</sub></th></tr></thead><tbody><tr><td>Elmshorn 1</td><td>775.6 ± 9.1</td><td>2343 ± 18</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Elmshorn 2</td><td>782.4 ± 9.0</td><td>2265 ± 15</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Average</td><td>779 ± 12</td><td>2306 ± 56</td><td>997</td><td>9</td><td>36</td><td>2.88–2.95</td><td>2.60–2.67</td></tr></tbody></table>

He is more volatile than Ar - suggests that no major resetting events occurred since ~2.8 Gyr. The age recorded could potentially represent the closure time after the catastrophic collision between H and L chondrite parent bodies and re-accretion of Elmshorn's parent body. The only slightly higher $T_4$ age (2.88–2.95 Gyr) relative to the $T_{40}$ age (2.60–2.67 Gyr) could be due to chemical heterogeneities within Elmshorn. For example, assuming a deviation of ±10% of the measured U, Th, and K concentrations would lead to an overlap between the $T_4$ (2.68–3.19 Gyr) and $T_{40}$ (2.47–2.82 Gyr) ages.

## Further Short- and Long-Lived Radionuclides by Gamma Spectrometry

For Elmshorn samples E01 and E02, the gamma lines were detected from members of the natural decay series of the primordial nuclides $^{238}$U and $^{232}$Th as well as of $^{40}$K

(Table 11) and short-lived cosmogenic nuclides. A total number of 12 cosmogenic radionuclides were detected above the decision thresholds of the method. Their half-lives range from 5.6 days ($^{52}$Mn) up to 705,000 years ($^{26}$Al).

The radionuclide data (Table 11) do not allow any statement about possible disequilibria in the decay series. However, assuming an equilibrium state of the decay series, the terrestrial isotope ratios, and a homogenous distribution in each sample, the U, Th, and K concentrations of the sample E01 would be 18.5 ± 2.2 ng g$^{-1}$, 42 ± 4 ng g$^{-1}$, and 910 ± 120 µg g$^{-1}$, respectively. For sample E02, U, Th, and K concentrations of 11.4 ± 1.3 ng g$^{-1}$, 47 ± 4 ng g$^{-1}$, and 750 ± 60 µg g$^{-1}$, respectively, were calculated. The values of both samples slightly differ from each other and compared with bulk compositional data obtained from Elmshorn fragment E03 (Table 5) showing the heterogeneity of the entire body.

<footnote><sup>a</sup>See text for constraint of upper limit.</footnote>
<table><caption>TABLE 11. Specific activities of radionuclides determined by gamma spectrometry. All activity data are referenced to the date of the respective falls, i.e., September 12, 2019 (Flensburg) and April 25, 2023 (Elmshorn: stones E01 and E02). Half-lives are from the Decay Data Evaluation Project (DDEP, 2023) or for <sup>26</sup>Al from Norris et al. (1983). Data about the German fall Flensburg, which occurred in close neighborhood, are included for comparison (Bischoff et al., 2021).</caption><thead><tr><th>Radionuclide</th><th>Half-life</th><th>Specific activity (dpm kg<sup>-1</sup>) Flensburg</th><th>σ (%)</th><th>Specific activity (dpm kg<sup>-1</sup>) Elmshorn (E01)</th><th>σ (%)</th><th>Specific activity (dpm kg<sup>-1</sup>) Elmshorn (E02)</th><th>σ (%)</th></tr></thead><tbody><tr><td colspan="8"><em>Cosmogenic</em></td></tr><tr><td><sup>7</sup>Be</td><td>53.22 days</td><td>121</td><td>14</td><td><strong>86</strong></td><td>20</td><td><strong>89</strong></td><td>11</td></tr><tr><td><sup>22</sup>Na</td><td>2.6029 years</td><td>65</td><td>8.8</td><td><strong>109</strong></td><td>13</td><td><strong>90</strong></td><td>8.1</td></tr><tr><td><sup>26</sup>Al</td><td>7.05 10<sup>5</sup> years</td><td>&lt;1.7</td><td></td><td><strong>56</strong></td><td>12</td><td><strong>46</strong></td><td>8.4</td></tr><tr><td><sup>46</sup>Sc</td><td>83.787 days</td><td>12.6</td><td>13</td><td><strong>10.7</strong></td><td>15</td><td><strong>11.1</strong></td><td>10</td></tr><tr><td><sup>44</sup>Ti<sup>a</sup></td><td>60.0 years</td><td>n.a.</td><td></td><td><strong>1.1</strong></td><td>26</td><td>&lt;1.7</td><td></td></tr><tr><td><sup>48</sup>V</td><td>15.9735 days</td><td>26</td><td>17</td><td></td><td></td><td><strong>21.8</strong></td><td>9.6</td></tr><tr><td><sup>51</sup>Cr</td><td>27.704 days</td><td>116</td><td>21</td><td></td><td></td><td><strong>95</strong></td><td>12</td></tr><tr><td><sup>52</sup>Mn</td><td>5.592 days</td><td>n.a.</td><td></td><td></td><td></td><td><strong>20</strong></td><td>15</td></tr><tr><td><sup>54</sup>Mn</td><td>312.19 days</td><td>150</td><td>8.0</td><td><strong>145</strong></td><td>12</td><td><strong>176</strong></td><td>7.8</td></tr><tr><td><sup>56</sup>Co</td><td>77.236 days</td><td>7.3</td><td>19</td><td><strong>8.4</strong></td><td>15</td><td><strong>7.1</strong></td><td>11</td></tr><tr><td><sup>57</sup>Co</td><td>271.81 days</td><td>13.5</td><td>13</td><td><strong>18.5</strong></td><td>12</td><td><strong>15.3</strong></td><td>8.5</td></tr><tr><td><sup>58</sup>Co</td><td>70.85 days</td><td>16.4</td><td>13</td><td><strong>12.2</strong></td><td>15</td><td><strong>16.5</strong></td><td>9.0</td></tr><tr><td><sup>60</sup>Co</td><td>5.2711 years</td><td>98</td><td>8.1</td><td><strong>2.9</strong></td><td>15</td><td><strong>4.3</strong></td><td>11</td></tr><tr><td colspan="8"><em>Primordial and decay series</em></td></tr><tr><td colspan="8"><sup>238</sup>U decay series</td></tr><tr><td><sup>238</sup>U</td><td>4.468 10<sup>9</sup> years</td><td>&lt;22</td><td></td><td><strong>&lt;35</strong></td><td></td><td><strong>&lt;60</strong></td><td></td></tr><tr><td><sup>226</sup>Ra</td><td>1600 years</td><td>13.3</td><td>11</td><td><strong>13.7</strong></td><td>12</td><td><strong>8.4</strong></td><td>11</td></tr><tr><td><sup>210</sup>Pb</td><td>22.23 years</td><td>&lt;27</td><td></td><td><strong>&lt;78</strong></td><td></td><td>&lt;110</td><td></td></tr><tr><td colspan="8"><sup>232</sup>Th decay series</td></tr><tr><td><sup>228</sup>Ra</td><td>5.75 years</td><td>&lt;24</td><td>15</td><td><strong>10.4</strong></td><td>15</td><td><strong>12.4</strong></td><td>15</td></tr><tr><td><sup>228</sup>Th</td><td>1.9126 years</td><td>16.6</td><td>13</td><td><strong>10.2</strong></td><td>11</td><td><strong>11.2</strong></td><td>10</td></tr><tr><td><sup>40</sup>K</td><td>1.2504 10<sup>9</sup> years</td><td>780</td><td>8.1</td><td><strong>1680</strong></td><td>13</td><td><strong>1400</strong></td><td>8.1</td></tr></tbody></table>

Note: Bold indicates the actual measured values.

Abbreviation: n.a., not analyzed.

<sup>a</sup>An equilibrium between <sup>44</sup>T and <sup>44</sup>Sc was assumed.

<table><caption>TABLE 12. Data about the saturation magnetization (Ms) and magnetic susceptibility (log χ) of different aliquots of the Elmshorn stones E03 and E07 analyzed at CEREGE. Analytical errors are negligible. For comparison data for H and L chondrites are given: (1) Ms average values from Gattacca et al. (2014): (2) log χ average values from Rochette et al. (2003).</caption><thead><tr><th>Stones</th><th>Sample type</th><th>Mass (mg)</th><th>Ms (Am<sup>2</sup> kg<sup>-1</sup>)</th><th>Log χ</th><th>Similar to:</th></tr></thead><tbody><tr><td>Elmshorn E03</td><td>(a) H6-fragment</td><td>238</td><td>32.4</td><td>5.30</td><td>H chondrites (1, 2)</td></tr><tr><td>Elmshorn E03</td><td>(b) Main lithology</td><td>267</td><td>40.0</td><td>5.10</td><td>H chondrites (1, 2)</td></tr><tr><td>Elmshorn E07</td><td>(c) Main lithology</td><td>427</td><td>20.4</td><td>5.01</td><td>L chondrites (1, 2)</td></tr><tr><td>E07—c1</td><td>Subsample</td><td>277</td><td>15.4</td><td>5.05</td><td>L chondrites (1, 2)</td></tr><tr><td>E07—c2</td><td>Subsample</td><td>150</td><td>29.6</td><td>4.93</td><td>L chondrites (1, 2)</td></tr><tr><td>H chondrites</td><td>Mean of falls (1,2)</td><td>Bulk</td><td>40.46</td><td>5.32</td><td></td></tr><tr><td>L chondrites</td><td>Mean of falls (1,2)</td><td>Bulk</td><td>17.93</td><td>4.87</td><td></td></tr></tbody></table>

Micro-Fourier Transform Infrared Spectroscopy

In order to study the spectroscopic characteristics of the rock, the three discernable lithologies from E03

(Figure 4c) were separately analyzed by micro-Fourier transform infrared (μ-FT-IR) spectroscopy. All three show a dominantly crystalline spectrum in the investigated areas. The dark fine-grained groundmass (related to the
<table><caption>TABLE 11. Specific activities of radionuclides determined by gamma spectrometry. All activity data are referenced to the date of the respective falls, i.e., September 12, 2019 (Flensburg) and April 25, 2023 (Elmshorn: stones E01 and E02). Half-lives are from the Decay Data Evaluation Project (DDEP, 2023) or for <sup>26</sup>Al from Norris et al. (1983). Data about the German fall Flensburg, which occurred in close neighborhood, are included for comparison (Bischoff et al., 2021).</caption><thead><tr><th>Radionuclide</th><th>Half-life</th><th>Specific activity (dpm kg<sup>-1</sup>) Flensburg</th><th>σ (%)</th><th>Specific activity (dpm kg<sup>-1</sup>) Elmshorn (E01)</th><th>σ (%)</th><th>Specific activity (dpm kg<sup>-1</sup>) Elmshorn (E02)</th><th>σ (%)</th></tr></thead><tbody><tr><td colspan="8"><em>Cosmogenic</em></td></tr><tr><td><sup>7</sup>Be</td><td>53.22 days</td><td>121</td><td>14</td><td><strong>86</strong></td><td>20</td><td><strong>89</strong></td><td>11</td></tr><tr><td><sup>22</sup>Na</td><td>2.6029 years</td><td>65</td><td>8.8</td><td><strong>109</strong></td><td>13</td><td><strong>90</strong></td><td>8.1</td></tr><tr><td><sup>26</sup>Al</td><td>7.05 10<sup>5</sup> years</td><td>&lt;1.7</td><td></td><td><strong>56</strong></td><td>12</td><td><strong>46</strong></td><td>8.4</td></tr><tr><td><sup>46</sup>Sc</td><td>83.787 days</td><td>12.6</td><td>13</td><td><strong>10.7</strong></td><td>15</td><td><strong>11.1</strong></td><td>10</td></tr><tr><td><sup>44</sup>Ti<sup>a</sup></td><td>60.0 years</td><td>n.a.</td><td></td><td><strong>1.1</strong></td><td>26</td><td>&lt;1.7</td><td></td></tr><tr><td><sup>48</sup>V</td><td>15.9735 days</td><td>26</td><td>17</td><td></td><td></td><td><strong>21.8</strong></td><td>9.6</td></tr><tr><td><sup>51</sup>Cr</td><td>27.704 days</td><td>116</td><td>21</td><td></td><td></td><td><strong>95</strong></td><td>12</td></tr><tr><td><sup>52</sup>Mn</td><td>5.592 days</td><td>n.a.</td><td></td><td></td><td></td><td><strong>20</strong></td><td>15</td></tr><tr><td><sup>54</sup>Mn</td><td>312.19 days</td><td>150</td><td>8.0</td><td><strong>145</strong></td><td>12</td><td><strong>176</strong></td><td>7.8</td></tr><tr><td><sup>56</sup>Co</td><td>77.236 days</td><td>7.3</td><td>19</td><td><strong>8.4</strong></td><td>15</td><td><strong>7.1</strong></td><td>11</td></tr><tr><td><sup>57</sup>Co</td><td>271.81 days</td><td>13.5</td><td>13</td><td><strong>18.5</strong></td><td>12</td><td><strong>15.3</strong></td><td>8.5</td></tr><tr><td><sup>58</sup>Co</td><td>70.85 days</td><td>16.4</td><td>13</td><td><strong>12.2</strong></td><td>15</td><td><strong>16.5</strong></td><td>9.0</td></tr><tr><td><sup>60</sup>Co</td><td>5.2711 years</td><td>98</td><td>8.1</td><td><strong>2.9</strong></td><td>15</td><td><strong>4.3</strong></td><td>11</td></tr><tr><td colspan="8"><em>Primordial and decay series</em></td></tr><tr><td colspan="8"><sup>238</sup>U decay series</td></tr><tr><td><sup>238</sup>U</td><td>4.468 10<sup>9</sup> years</td><td>&lt;22</td><td></td><td><strong>&lt;35</strong></td><td></td><td><strong>&lt;60</strong></td><td></td></tr><tr><td><sup>226</sup>Ra</td><td>1600 years</td><td>13.3</td><td>11</td><td><strong>13.7</strong></td><td>12</td><td><strong>8.4</strong></td><td>11</td></tr><tr><td><sup>210</sup>Pb</td><td>22.23 years</td><td>&lt;27</td><td></td><td><strong>&lt;78</strong></td><td></td><td>&lt;110</td><td></td></tr><tr><td colspan="8"><sup>232</sup>Th decay series</td></tr><tr><td><sup>228</sup>Ra</td><td>5.75 years</td><td>&lt;24</td><td>15</td><td><strong>10.4</strong></td><td>15</td><td><strong>12.4</strong></td><td>15</td></tr><tr><td><sup>228</sup>Th</td><td>1.9126 years</td><td>16.6</td><td>13</td><td><strong>10.2</strong></td><td>11</td><td><strong>11.2</strong></td><td>10</td></tr><tr><td><sup>40</sup>K</td><td>1.2504 10<sup>9</sup> years</td><td>780</td><td>8.1</td><td><strong>1680</strong></td><td>13</td><td><strong>1400</strong></td><td>8.1</td></tr></tbody></table>

Note: Bold indicates the actual measured values.

Abbreviation: n.a., not analyzed.

<sup>a</sup>An equilibrium between <sup>44</sup>T and <sup>44</sup>Sc was assumed.

<table><caption>TABLE 12. Data about the saturation magnetization (Ms) and magnetic susceptibility (log χ) of different aliquots of the Elmshorn stones E03 and E07 analyzed at CEREGE. Analytical errors are negligible. For comparison data for H and L chondrites are given: (1) Ms average values from Gattacceca et al. (2014): (2) log χ average values from Rochette et al. (2003).</caption><thead><tr><th>Stones</th><th>Sample type</th><th>Mass (mg)</th><th>Ms (Am<sup>2</sup> kg<sup>-1</sup>)</th><th>Log χ</th><th>Similar to:</th></tr></thead><tbody><tr><td>Elmshorn E03</td><td>(a) H6-fragment</td><td>238</td><td>32.4</td><td>5.30</td><td>H chondrites (1, 2)</td></tr><tr><td>Elmshorn E03</td><td>(b) Main lithology</td><td>267</td><td>40.0</td><td>5.10</td><td>H chondrites (1, 2)</td></tr><tr><td>Elmshorn E07</td><td>(c) Main lithology</td><td>427</td><td>20.4</td><td>5.01</td><td>L chondrites (1, 2)</td></tr><tr><td>E07—c1</td><td>Subsample</td><td>277</td><td>15.4</td><td>5.05</td><td>L chondrites (1, 2)</td></tr><tr><td>E07—c2</td><td>Subsample</td><td>150</td><td>29.6</td><td>4.93</td><td>L chondrites (1, 2)</td></tr><tr><td>H chondrites</td><td>Mean of falls (1,2)</td><td>Bulk</td><td>40.46</td><td>5.32</td><td></td></tr><tr><td>L chondrites</td><td>Mean of falls (1,2)</td><td>Bulk</td><td>17.93</td><td>4.87</td><td></td></tr></tbody></table>

Micro-Fourier Transform Infrared Spectroscopy

In order to study the spectroscopic characteristics of the rock, the three discernable lithologies from E03

(Figure 4c) were separately analyzed by micro-Fourier transform infrared (μ-FT-IR) spectroscopy. All three show a dominantly crystalline spectrum in the investigated areas. The dark fine-grained groundmass (related to the
<figure><img src="image_8.png" /><figcaption>FIGURE 7. (a) Part of a dark fragment from E03 (~0.5 cm in apparent size) containing several chondrules and chondrule fragments. The clast has a sharp boundary to the brecciated main portion of the rock (plane polarized light). (b) Area within the dark lithology. Small irregularly shaped metal grains (white) are homogeneously distributed and probably responsible for the dark appearance (BSE image). (c) Phosphate (gray)-chromite (light gray) paragenesis (BSE image). (d) Al-rich relict chondrule within the dark lithology; skeletal olivines embedded in a crystalline Na,Al-rich groundmass (BSE image).</figcaption></figure>

dark clast in Figure 4a) and the bulk mass of the light clast (Figure 4b) both display olivine-dominated spectra. The olivine observed in the light lithology shows bands consistent with a high Fo portion at 1030, 971, 923, 893, 833, and 620 cm⁻¹. The finer grained groundmass of the dark lithology shows rather attenuated Reststrahlen and combination bands at 1003, 973¹, 886, and 832 cm⁻¹ with additional, rather less defined peaks between 952 and 900 cm⁻¹. The finer grained dominating lithology (the clastic groundmass: medium-light: Figure 4c) appears to be dominated by a low-Ca pyroxene and shows additional Reststrahlen bands (RB; i.e., RBs are reflectance maxima that are mineral diagnostic) at 724, 685, and 644 cm⁻¹. Mineral diagnostic spectral features, for example, the Christiansen feature (CF), or the mineral diagnostic RBs are indicated in Figure 15 as CF and black arrows. The

CF alternates between 1140 and 1135 cm⁻¹ in the bulk measurements.

## Density Measurements

Published values for the densities of H chondrites and L chondrites are 3.42 ± 0.18 g cm⁻³ and 3.36 ± 0.16 g cm⁻³, respectively (Consolmagno et al., 2008). The density of several Elmshorn fragments were measured. The volume of one piece (E02) of 233.5 ± 0.1 g was obtained by two techniques: first, by a method described by Consolmagno et al. (2008) and, second, by CT procedures. The first type of measurement led to a volume of 70.0 ± 1.0 cm³ (n = 13) and a density (ρ) of 3.34 ± 0.05 g cm⁻³. For the same 233.5 g piece, the high-precision CT technique led to a volume of 69.73 cm³ and a
<figure><img src="image_9.png" /><figcaption>FIGURE 7. (a) Part of a dark fragment from E03 (~0.5 cm in apparent size) containing several chondrules and chondrule fragments. The clast has a sharp boundary to the brecciated main portion of the rock (plane polarized light). (b) Area within the dark lithology. Small irregularly shaped metal grains (white) are homogeneously distributed and probably responsible for the dark appearance (BSE image). (c) Phosphate (gray)-chromite (light gray) paragenesis (BSE image). (d) Al-rich relict chondrule within the dark lithology; skeletal olivines embedded in a crystalline Na,Al-rich groundmass (BSE image).</figcaption></figure>

dark clast in Figure 4a) and the bulk mass of the light clast (Figure 4b) both display olivine-dominated spectra. The olivine observed in the light lithology shows bands consistent with a high Fo portion at 1030, 971, 923, 893, 833, and 620 cm⁻¹. The finer grained groundmass of the dark lithology shows rather attenuated Reststrahlen and combination bands at 1003, 973¹, 886, and 832 cm⁻¹ with additional, rather less defined peaks between 952 and 900 cm⁻¹. The finer grained dominating lithology (the clastic groundmass: medium-light: Figure 4c) appears to be dominated by a low-Ca pyroxene and shows additional Reststrahlen bands (RB; i.e., RBs are reflectance maxima that are mineral diagnostic) at 724, 685, and 644 cm⁻¹. Mineral diagnostic spectral features, for example, the Christiansen feature (CF), or the mineral diagnostic RBs are indicated in Figure 15 as CF and black arrows. The

CF alternates between 1140 and 1135 cm⁻¹ in the bulk measurements.

## Density Measurements

Published values for the densities of H chondrites and L chondrites are 3.42 ± 0.18 g cm⁻³ and 3.36 ± 0.16 g cm⁻³, respectively (Consolmagno et al., 2008). The density of several Elmshorn fragments were measured. The volume of one piece (E02) of 233.5 ± 0.1 g was obtained by two techniques: first, by a method described by Consolmagno et al. (2008) and, second, by CT procedures. The first type of measurement led to a volume of 70.0 ± 1.0 cm³ (n = 13) and a density (ρ) of 3.34 ± 0.05 g cm⁻³. For the same 233.5 g piece, the high-precision CT technique led to a volume of 69.73 cm³ and a
<figure><img src="image_9.png" /><figcaption>FIGURE 8. Olivine compositions (Fa in mole%): (a) of bulk sample of E03; (b) of bulk sample of E07; (c) olivine compositions of the H6 and dark fragment (see Figure 4; E03); (d) olivine compositions of five type H/L or L3.9-4 fragments from E03. Chemical details are given in Table 1.</figcaption></figure>

density (ρ) of 3.349 ± 0.010 g cm⁻³. Thus, both values are similar (mean: 3.344 g cm⁻³). Using the CT technique, the volume of a second piece from a different individual object (E03) from the meteorite strewn field of 51.62 g was obtained and found to be 14.97 cm³. These data lead to a density of 3.448 ± 0.010 g cm⁻³. By digital optical techniques, the volume of the largest piece (E01) was found to be 1119.105 cm³. Considering its mass of 3731 g, a density of 3.334 ± 0.003 g cm⁻³ is calculated. Thus, two stones have densities of about 3.34 g cm⁻³, while the third one has a significantly higher density of 3.45 g cm⁻³.

Considering the obtained density values, the E03 fragment has a similar value to that of mean H chondrites, whereas the pieces of E01 and E02 have similar densities to those obtained for mean L chondrites.

## Magnetic Susceptibility

The (MS) of different fragments of the Elmshorn breccia analyzed in Nördlingen indicate a wide range of values (Table S3). The weighted overall mean value of $log\chi = 5.07 \pm 0.03$ (with $\chi$ in $10^{-9} m^3 kg^{-1}$) is in between the average values of $4.87 \pm 0.10$ and $5.32 \pm 0.10$ for falls of L and H chondrites, respectively (Rochette et al., 2003). Large samples ($>\sim 10$ g) including the main mass plot within a kind of transition zone between H and L chondrites. The values for small samples scatter in a wide range around the average with a majority tending toward L and only few ones to H chondrite lithologies. Similarly, the values for the MS of different aliquots from E03 cover a large field between the mean values for H and L chondrites (Figure 16). The scattering indicates inhomogeneities in the distribution of ferromagnetic metal on a scale of centimeters to millimeters and corresponds to a range of roughly 7–13 wt%.

Two samples from the E03 fragment without fusion crust were studied at CEREGE: a 267 mg bulk slice and a 238 mg fragment of type 6 lithology (Table 12). The two samples gave similar results and were aggregated. The mean MS $log \chi = 5.21$ (where $\chi$ is in $10^{-9} m^3 kg^{-1}$: analytical errors are negligible) is within the expected range for an H chondrite fall ($5.32 \pm 0.10$, n = 144; Rochette et al., 2003). Saturation magnetization $M_S = 37.1 Am^2 kg^{-1}$ is also within the expected range for H chondrite falls ($40.46 \pm 6.99 Am^2 kg^{-1}$: n = 25; Gattacceca et al., 2014). The 437 mg sample from stone E07, which was selected based on the low $log \chi$ values (Figure 16) for comparison, clearly shows different results. The Ms value, which is the best proxy for the metal abundance, is close to that of L chondrite falls (Table 12: $17.93 \pm 6.09$: n = 31; Gattacceca et al., 2014).
<figure><img src="image_10.png" /><figcaption>FIGURE 8. Olivine compositions (Fa in mole%): (a) of bulk sample of E03; (b) of bulk sample of E07; (c) olivine compositions of the H6 and dark fragment (see Figure 4; E03); (d) olivine compositions of five type H/L or L3.9-4 fragments from E03. Chemical details are given in Table 1.</figcaption></figure>

density (ρ) of 3.349 ± 0.010 g cm⁻³. Thus, both values are similar (mean: 3.344 g cm⁻³). Using the CT technique, the volume of a second piece from a different individual object (E03) from the meteorite strewn field of 51.62 g was obtained and found to be 14.97 cm³. These data lead to a density of 3.448 ± 0.010 g cm⁻³. By digital optical techniques, the volume of the largest piece (E01) was found to be 1119.105 cm³. Considering its mass of 3731 g, a density of 3.334 ± 0.003 g cm⁻³ is calculated. Thus, two stones have densities of about 3.34 g cm⁻³, while the third one has a significantly higher density of 3.45 g cm⁻³.

Considering the obtained density values, the E03 fragment has a similar value to that of mean H chondrites, whereas the pieces of E01 and E02 have similar densities to those obtained for mean L chondrites.

## Magnetic Susceptibility

The (MS) of different fragments of the Elmshorn breccia analyzed in Nördlingen indicate a wide range of values (Table S3). The weighted overall mean value of $log\chi = 5.07 \pm 0.03$ (with $\chi$ in $10^{-9} m^3 kg^{-1}$) is in between the average values of $4.87 \pm 0.10$ and $5.32 \pm 0.10$ for falls of L and H chondrites, respectively (Rochette et al., 2003). Large samples ($>\sim 10$ g) including the main mass plot within a kind of transition zone between H and L chondrites. The values for small samples scatter in a wide range around the average with a majority tending toward L and only few ones to H chondrite lithologies. Similarly, the values for the MS of different aliquots from E03 cover a large field between the mean values for H and L chondrites (Figure 16). The scattering indicates inhomogeneities in the distribution of ferromagnetic metal on a scale of centimeters to millimeters and corresponds to a range of roughly 7–13 wt%.

Two samples from the E03 fragment without fusion crust were studied at CEREGE: a 267 mg bulk slice and a 238 mg fragment of type 6 lithology (Table 12). The two samples gave similar results and were aggregated. The mean MS $log \chi = 5.21$ (where $\chi$ is in $10^{-9} m^3 kg^{-1}$: analytical errors are negligible) is within the expected range for an H chondrite fall ($5.32 \pm 0.10$, n = 144; Rochette et al., 2003). Saturation magnetization $M_S = 37.1 Am^2 kg^{-1}$ is also within the expected range for H chondrite falls ($40.46 \pm 6.99 Am^2 kg^{-1}$: n = 25; Gattacceca et al., 2014). The 437 mg sample from stone E07, which was selected based on the low $log \chi$ values (Figure 16) for comparison, clearly shows different results. The Ms value, which is the best proxy for the metal abundance, is close to that of L chondrite falls (Table 12: $17.93 \pm 6.09$: n = 31; Gattacceca et al., 2014).
<figure><img src="image_10.png" /><figcaption>FIGURE 9. (a) Fragment of an impact melt lithology with metal-sulfide spherules and some relict olivines clasts of Fa$_{29}$ and Fa$_{20.5}$ (BSE image); (b) fragment containing veins like features rich in metals and sulfides that probably formed by shock (BSE image); (c) shock-darkened fragments with metals and sulfides coating all fractures and spaces of the silicates (BSE image); (d) sulfides embedding silicate clasts (reflected light); (e) porous vein-like area with metals (often Ni-poor [~2 wt%]) and sulfides of unusual morphology (BSE image); (f) several millimeter-sized, vein-like metal-sulfide associations (reflected light). All images from sample E03.</figcaption></figure>
<figure><img src="image_11.png" /><figcaption>FIGURE 9. (a) Fragment of an impact melt lithology with metal-sulfide spherules and some relict olivines clasts of Fa$_{29}$ and Fa$_{20.5}$ (BSE image); (b) fragment containing veins like features rich in metals and sulfides that probably formed by shock (BSE image); (c) shock-darkened fragments with metals and sulfides coating all fractures and spaces of the silicates (BSE image); (d) sulfides embedding silicate clasts (reflected light); (e) porous vein-like area with metals (often Ni-poor [~2 wt%]) and sulfides of unusual morphology (BSE image); (f) several millimeter-sized, vein-like metal-sulfide associations (reflected light). All images from sample E03.</figcaption></figure>
<figure><img src="image_11.png" /></figure>

FIGURE 10. Triple oxygen isotope compositions (Δ¹⁷O vs. δ¹⁸O) of eight individual chips (~2 mg each) from two different fragments of Elmshorn (E03, E07) in comparison with the compositions of ordinary chondrites (H, L, LL) and other noncarbonaceous clan meteorites (Ang, angrites; Aub, aubrites; Bra, brachinites; EC, enstatite chondrites; HED, howardites, eucrites, diogenites; SNC, shergottites, nakhlites, chassignites) and the bulk silicate Earth (BSE). Meteorite reference compositions were compiled from the Meteoritical Bulletin Database and are shown with Kernel density estimation contours, with the outermost contours for a given meteorite group encompassing 70% of the corresponding data populations. The composition of the BSE was taken from Peters et al. (2021).

The MS (log χ) gives more or less the same result but is less robust considering the metal abundance.

The hysteresis properties, with very low coercivity ($B_C$=2.9 mT), low $M_{RS}/M_S$ (1.16×10⁻²), and high $B_{CR}/B_C$ (30.0) are typical of equilibrated H chondrites, with induced magnetic properties dominated by multidomain kamacite (Gattacceca et al., 2014). The $S_{-300}$ value of 0.51 indicates the presence of significant high-coercivity ferromagnetic minerals that can be identified as tetrataenite in the cloudy zone structure (Gattacceca et al., 2014). The coercivity spectra derived from IRM acquisition for the two samples can be fitted with two components with coercivity peaks at 4.7 and 143 mT (238 mg sample), and 65 and 353 mT (267 mg sample). Although there is some significant intersample variability, the existence of a component with very high coercivity indicates that the tetrataenite in the cloudy zone microstructure is ordered.

The two Elmshorn samples from stone E03 have magnetic properties typical of equilibrated H chondrites. This result is expected for the H6 clast and shows that the second sample of the stone representing the fine-grained clastic main lithology is also dominated by H chondrite components. The magnetic properties show a rock with metal under the form of multidomain kamacite and remanence properties dominated by the cloudy zone microstructure with high coercivity.

<figure><img src="image_12.png" /></figure>

FIGURE 11. The Ti isotope composition of Elmshorn (gray star) is consistent with both the simultaneously analyzed OC Forest Vale and literature values of individual OCs (yellow symbols). The data reveal deficits in $ε^{46}$Ti and $ε^{50}$Ti relative to Earth, indicating their formation in the inner solar system, i.e., the NC (noncarbonaceous meteorite) reservoir. Colored fields represent averages of meteorite groups (line) with 2 SD uncertainty (envelope) based on literature data (for data compilation and references, see Rüfenacht et al., 2023). Individual data points represent bulk meteorite samples, which were analyzed in the same laboratory as Elmshorn at ETH Zurich and are published in Rüfenacht et al. (2023). Aca, acapulcoites; EC, enstatite chondrites; Meso, mesosiderites; OC, ordinary chondrites. Literature data of OCs are from Trinquier et al. (2009), Zhang et al. (2011, 2012), Williams (2015), Burkhardt et al. (2017), Bischoff et al. (2017), Bischoff, Barrat, et al. (2019), Gerber et al. (2017), Williams et al. (2021), and Rüfenacht et al. (2023). Figure adapted from Rüfenacht et al. (2023).

This high coercivity indicates that the tetrataenite in the cloudy zone was not disordered by transient thermal events following its formation during parent body metamorphic cooling, indicating the absence of shock above shock level S3 (Dos Santos et al., 2015; Gattacceca et al., 2014).

The sample from stone E07 shows completely different magnetic properties. It can be characterized by significantly lower metal abundance and the values for magnetic properties are very close to those of L chondrites. However, it should be considered that on such small samples (Table 12) it is difficult to be definitive, because Ms depends on the relative abundance of kamacite, taenite, and tetrataenite (higher nickel leads to lower Ms). Thus, a large kamacite grain or a large taenite grain can affect the result significantly.