# Phosphorus-rich grains in Ryugu samples with major biochemical potential

C. Pilorget, Donia Baklouti, J. -P. Bibring, R. Brunetto, M. Ito, I. Franchi, N.

Tomioka, M. Uesugi, A. Yamaguchi, R. Greenwood, et al.

► To cite this version:

C. Pilorget, Donia Baklouti, J. -P. Bibring, R. Brunetto, M. Ito, et al. Phosphorus-rich grains in Ryugu samples with major biochemical potential. Nature Astronomy, 2024, 8, pp.1529-1535. 10.1038/s41550-024-02366-w. insu-04843859

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# Phosphorus-rich grains in Ryugu samples with major biochemical potential

Received: 5 February 2024

Accepted: 20 August 2024

Published online: 25 September 2024

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C. Pilorget Ⓔ¹,²✉, D. Baklouti Ⓔ¹, J.-P. Bibring¹, R. Brunetto¹, M. Ito Ⓔ³,⁴,
I. Franchi Ⓔ⁵, N. Tomioka Ⓔ³, M. Uesugi Ⓔ⁶, A. Yamaguchi Ⓔ⁷, R. Greenwood⁵,
T. Okada Ⓔ⁸,⁹, T. Usui Ⓔ⁸,⁹, T. Yada Ⓔ⁸, K. Hataakeda⁸,¹⁰, K. Yogata Ⓔ⁸, D. Loizeau¹,
T. Le Pivert-Jolivet¹, T. Jiang¹,¹¹, J. Carter Ⓔ¹, V. Hamm¹, M. Abe⁸,¹²,
A. Aléon-Toppani Ⓔ¹, F. Borondics Ⓔ¹³, Y. Enokido⁸, Y. Hitomi⁸,¹⁰, N. Imae Ⓔ⁷,
Y. Karouji Ⓔ¹⁴, K. Kumagai⁸,¹⁰, M. Kimura Ⓔ⁷, Y. Langevin¹, C. Lantz¹, M.-C. Liu¹⁵,
M. Mahlke Ⓔ¹, A. Miyazaki Ⓔ⁸, Z. Mughal Ⓔ⁵, K. Nagashima⁸, A. Nakano⁸,
A. Nakata⁸, A. Nakato Ⓔ⁷, M. Nishimura⁸, T. Ohigashi Ⓔ¹⁶, T. Ojima Ⓔ⁸, F. Poulet¹,
L. Riu¹⁷, N. Shirai Ⓔ¹⁸, Y. Sugiyama⁸, R. Tahara⁸, K. Uesugi Ⓔ⁶, M. Yasutake⁶,
H. Yuzawa Ⓔ¹⁹, A. Moussi-Soffys²⁰, S. Nakazawa Ⓔ⁸, T. Saiki⁸, F. Terui²¹,
M. Yoshikawa⁸, S. Tanaka⁸,¹²,²², S. Watanabe Ⓔ²³ & Y. Tsuda⁸,¹²

Parent bodies of C-type asteroids may have brought key volatile and organic-rich compounds to the terrestrial planets in the early stages of the Solar System. At the end of 2020, the JAXA Hayabusa2 mission successfully returned samples from Ryugu, providing access to a primitive matter that has not suffered terrestrial alteration. Here we report the discovery of a peculiar class of grains, up to a few hundreds of micrometres in size, that have a hydrated ammonium–magnesium–phosphorus (HAMP)-rich composition. Their specific chemical and physical properties point towards an origin in the outer Solar System, beyond most snow lines, and their preservation along Ryugu history. These phosphorus-rich grains, embedded within an organic-rich phyllosilicate matrix, may have played a major role when immersed in primitive terrestrial water reservoirs. In particular, in contrast to poorly soluble calcium-rich phosphates, HAMP grains favour the release of phosphorus-rich and nitrogen-rich ionic species, to enter chemical reactions. HAMP grains may have thus critically contributed to the reaction pathways of organic matter towards a biochemical evolution.

On 6 December 2020, the Japanese Space Agency (JAXA) Hayabusa2 mission successfully returned to Earth ~5.4 g of samples collected at the surface of the C-type asteroid Ryugu¹. 'Chamber A' particles were collected on the natural surface of Ryugu, while 'chamber C' particles were collected close to an artificial crater so as to possibly access the subsurface. These samples are stored and curated in an ultraclean and controlled N₂-purged environment in the JAXA-Institute of Space and Astronautical Science (ISAS) Curation Facility and have thus remained unexposed to the terrestrial atmosphere since their collection. In this

facility, a global non-destructive and non-invasive characterization of these samples is being performed. In particular, the MicrOmega near-infrared (NIR) hyperspectral microscope has identified inclusions and grains, some with sizes up to a few hundreds of micrometres of a variety of composition: organics, NH-rich and OH-rich phases as well as minerals such as carbonates²,³ all embedded within a dark matrix (NIR reflectance factor of 2–3%) primarily made of phyllosilicates¹,⁴⁻⁸. In this Article, we focus on one class of grains/inclusions that uniquely exhibits a reflectance factor about four to ten times higher than the matrix and
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**Fig. 1 | IR spectral characterization.** *a.* NIR reflectance spectra obtained by MicrOmega in the Curation Center on HAMP-rich areas shown in Fig. 4. The vertical lines are set at 2.03, 2.15, 2.725, 3.06 and 3.28 µm. Spectra A, B, C and D correspond to the spectra of the HAMP-rich areas in Fig. 4a, b, c and d, respectively. *b.* MIR reflectance spectra by the micro-spectro-imager of regions S1 (HAMP-rich) and S2 (matrix-rich) shown in Fig. 2c. The blue arrows respectively point towards N-H (at 6.9 µm) and P-O (at -9.5 µm) features. The green arrows

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point towards (H–)O–H features at ~3 µm and ~6 µm due to endogenous water and possibly water from terrestrial contamination since the samples were exposed to the terrestrial atmosphere for MIR spectroscopic analyses. The dotted lines show the Christiansen feature for both S1 (in black) and S2 (in grey) spectra. The P–O feature at ~9.5 µm is present as a peak since it is the surface scattering regime at wavelengths >8 µm, and is distinct from the Si–O feature at ~10 µm that can be observed on areas where matrix material is present.

a very peculiar broad and deep '3 µm' absorption feature (Fig. 1a). This feature is attributed to O-H stretching vibrations of H₂O molecules (for example, refs. 9,10). The position of this absorption band, beyond 3 µm, and its remarkably large width point towards particularly strong hydrogen bonds with different electronic environments (for example, ref. 11). Notably, this feature, which is not present in the matrix and other minerals, has been observed through the NIR spectra acquired in the Curation Center, where the samples were always maintained in an H₂O-free environment since their collection. This observation implies that the H₂O molecules present in these high-reflectance grains are non-terrestrial. The spectra of these peculiar grains also display a sharp band at ~2.7 µm shifted by ~10 nm towards longer wavelengths compared with the feature exhibited by the phyllosilicates present in the matrix<sup>2,12</sup>, as well as additional bands between 2.0 and 2.2 µm for the larger grains (Fig. 1a).

## Extended characterization after extraction

To refine their composition, two grains with these spectral properties were extracted from aggregate samples, one from C0209 (Fig. 2) and the other from A0218 (Extended Data Fig. 1) for complementary characterization. Combined analyses were then performed at the Kochi Institute for Core Sample Research of Japan Agency for Marine-Earth Science and Technology (JAMSTEC, Japan), Institut d'Astrophysique Spatiale (France) and Open University (UK).

Scanning electron microscopy (SEM)-energy-dispersive spectroscopy (EDS) analyses revealed an elemental composition primarily made of phosphorus, oxygen and magnesium (Fig. 3, Extended Data Figs. 2 and 3 and Extended Data Table 1) with the atomic ratio P/Mg of ~1 and almost no silicon (the prime constituent of the matrix silicates) nor calcium (Ca/Mg is below the per cent level) (Extended Data Table 2, point 6 and Extended Data Table 3, points 11, 12 and 14). Some sodium also appears collocated with phosphorus in these grains (Fig. 3), at a low abundance and highly variable level (Na/Mg <1%; Extended Data Tables 2 and 3). In addition, this phosphorus-based compound appears poorly crystalline from X-ray diffraction (XRD) analyses, at least at

the scale of a few tens of micrometres (Extended Data Fig. 4). Further analysis by mid-infrared (MIR) micro-spectro-imagery (2.5–12 µm) has been carried out at the SOLEIL Synchrotron facility (SMIS beamline) to complement the MicrOmega NIR (0.99–3.60 µm) characterization performed within the Curation Center (Figs. 1b and 2 and Extended Data Fig. 1). Notably, correlated features at 3 µm and 6.9 µm, and a broader one centred around 9.5 µm have been observed on the P–O–Mg-rich areas (Extended Data Fig. 5). The ~9.5 µm spectral feature is attributed to P–O stretching vibrations (for example, refs. 13,14). The 6.9 µm band is attributed to the out-of-plane bending vibration (ν₄) in NH₄⁺ (for example, refs. 15–17). This identification is consistent with the presence in MicrOmega spectral data acquired in the Curation Center of a double peak feature at ~2.03 and ~2.15 µm (respectively attributed to NH₄⁺ν₂ + ν₃ and ν₃ + ν₄ combination modes<sup>17,18</sup>) for the larger grains, as well as small ~3.06–3.10 µm and ~3.25–3.30 µm features, respectively due to the asymmetric and symmetric stretching vibrations in NH₄⁺ (for example, refs. 17,19,20) observed in some cases within the broad 3 µm band.

Although each analytical method alone is insufficient to provide definite answers about what the analysed grains are, the combination of NIR/MIR spectroscopy and SEM/EDS elemental composition data offers a key diagnostic: Ryugu contains hydrated ammonium-magnesium-phosphorus (HAMP)-rich grains in which phosphorus is oxidized, plausibly as phosphate. In addition, these HAMP grains are most likely an ionic solid stabilized by the structural H₂O (for example, ref. 21) thanks to strong hydrogen bonds with NH₄⁺ and P-O-rich ions.

## Discussion

While only a limited number of extracted grains were fully characterized outside the Curation Facility, HAMP grains and inclusions are commonly present in Ryugu samples, as identified by the MicrOmega analyses. Several tens of areas with sizes up to a few hundred micrometres have been highlighted (examples in Fig. 4). Inclusions at scales smaller than the MicrOmega spatial resolution (~20 µm) are also likely to exist as several detections are close to the detection limit.
<figure><img src="image_5.png" /><figcaption>**Fig. 2 | C0209-extracted particle.** a, Visible image of the grain extracted from CO209 aggregate sample obtained with an optical microscope. b, Reflectance (R) map at 2.58 µm. c, The same as b with the location (red boxes) of spectra displayed in Fig. 1. d, A 3 µm relative band depth (BD) map. e, A 6.9 µm relative band depth (BD) map. f, A 9.5 µm relative band depth (BD) map. These maps are based on spectral features shown in Fig. 1b. Pixels with a reflectance factor at 2.58 µm lower than 0.03 (corresponding to the absence of Ryugu material) have been removed from d–f.</figcaption></figure>

The other ubiquitous P–O-rich compound found in Ryugu samples is the Ca-phosphate apatite$^{5–7}$, also detected in carbonaceous chondrites (for example, refs. 22,23). Minerals from the apatite group are poorly soluble (Extended Data Table 4). In the case of Ryugu samples, apatite was mostly observed in the form of hydroxyapatite (Ca$_5$(PO$_4$)$_3$(OH)). In addition, the presence of phosphides (schreibersite (Fe, Ni)$_3$P and allabogdanite (Fe, Ni)$_2$P) has been reported in the least altered fragments$^6$, as well as a few Mg-phosphate-rich areas, some with small amounts of Na (refs. 5–7,24).

The formation of HAMP grains, by contrast to the other P–O-rich ionic solid hydroxyapatite, puts strong constraints on the formation and evolution of Ryugu’s parent body. The synthesis of HAMP requires that Ca$^{2+}$ ions be highly depleted relative to Mg$^{2+}$ ions, while phosphorus, plausibly initially present in phosphide compounds, had already been oxidized. The scenario we propose to account for the favoured formation of HAMP with respect to Ca-phosphates is determined by the larger availability of Mg$^{2+}$ (and NH$_4^+$) ions compared with Ca$^{2+}$, as a result of the competing formation of Ca-rich carbonates. The early availability of Ca$^{2+}$ and CO$_3^{2-}$, the latter of which possibly originated from ices$^6$, would have favoured the formation of Ca-rich carbonates$^3$. The resulting huge depletion in Ca$^{2+}$ relative to Mg$^{2+}$, and an increasing availability of P–O-rich ions, led to the formation of HAMP. This scenario is supported by the detections of calcium carbonates, phosphides and ‘Mg–Na phosphates’ in the least altered fragments of Ryugu, while no hydroxyapatite was observed in those samples$^6$. Similarly, ref. 25 reported the presence in Orgueil of Ca-carbonates in a clast that shows little alteration, with no detectable apatite content.

With some Ca$^{2+}$ ions remobilized and some PO$_4^{3-}$ ions still available or also remobilized, apatites would have formed, at least in some localized sites, as is observed in Ryugu samples. The formation of

(Mg,Fe)-carbonates (such as breunnerite) would have occurred when Ca$^{2+}$ ions were no longer available, after that of (Mg,Ca)-carbonates (such as dolomite) and apatites. This scenario would be consistent with the suggestion by ref. 3 that dolomite formed within small pores present in the precursor material, while the formation of Fe-rich magnesite (breunnerite) occurred later in larger fractures.

The presence of ammonium cations NH$_4^+$ within the HAMP compounds supports the suggested scenario that Ryugu’s parent body formed in the outer Solar System, beyond H$_2$O, NH$_3$ and CO$_2$ snow lines$^{3,4,6,26–28}$, in particular for requiring NH$_4^+$ ions, a major specie detected in extraterrestrial matter (for example, refs. 29,30), probably trapped in ices. Similar to CO$_3^{2-}$ ions, NH$_4^+$ can thus be readily available to enter reaction processes within the accreted Ryugu parent body, possibly at icy grain surfaces, and form ionic solids such as HAMP grains. The same process could also account for the coupled inclusion of structural H$_2$O molecules responsible for the large 3 µm feature that was detected exclusively in these grains. Water molecules are indeed mostly absent from the matrix$^{31,32}$, in which the hydroxyl moiety (M–OH) is detected through the 2.7 µm absorption band (for example, ref. 12). Some water molecules together with ammonium cations would thus have been trapped in HAMP inclusions and would constitute unique remnants from the primary ices.

The importance of the detection of HAMP grains/inclusions in Ryugu samples comes from their much higher solubility in liquid water with respect to apatites. Solubility is indeed directly related to the lattice energy of the different ionic solids at stake and to the hydration enthalpy of the different ions forming the compound. First, because of its smaller size, Mg$^{2+}$ has a much lower hydration enthalpy than Ca$^{2+}$ that makes it easily solvated. Then, apatite is by far the ionic structure with the strongest lattice energy among the different phosphates
<figure><img src="image_6.png" /><figcaption>**Fig. 3 | Elemental analysis.** EDS maps of a fraction of the particle extracted from CO209 (from the white part observed in Fig. 2a). The extracted material was pressed on a gold foil and observed in SEM (left image). The black rectangle on the SEM image indicates the area analyzed by EDS (right). EDS data indicate that</figcaption></figure>

P-rich areas are Si-free, and conversely: Si is a major constituent of the matrix and is not detected in the P-rich grains. Importantly, the P-rich area includes Mg but no Ca, excluding apatite.

<figure><img src="image_7.png" /><figcaption>**Fig. 4 | Examples of HAMP grains.** a–d, False-colour RGB (red, green, blue) maps (R: 3.2 µm, G: 2.8 µm, B: 2.5 µm, square-root stretch) of selected regions in which grains/inclusions with spectral signatures similar to the extracted particle are observed. The HAMP-rich areas display a blue colour and are indicated by white arrows. Observations were performed in the Curation Center on bulk ‘A3’ (third bulk sample from chamber A) (a), ‘aggregate’ samples CO209 (b) and C0107 (c), and grain A0001 (d). Averaged spectra of the HAMP-rich areas are shown in Fig. 1a. Artefacts due to shadowing can be observed on the edges of the grain in d.</figcaption></figure>

(and carbonates) identified. This parameter characterizes the stability of the ionic solids and, thus, their ability to be thermodynamically favoured if the contributing ions are available, and reversely, it will affect their solubility in liquid water. As a result, hydroxyapatite is the least soluble specie among the above-mentioned list of compounds (Extended Data Table 4). Comparatively, the solubility of struvite (NH₄MgPO₄·6H₂O), the best well-characterized compositional analogue to HAMP compounds, is more than two orders of magnitude higher than that of hydroxyapatite in water at 298 K (Extended Data

Table 4). In the competition between the formation of Ca-phosphates and Mg-phosphates, hydroxyapatite is thus strongly favoured provided that Ca²⁺ and PO₄³⁻ ions are available.

As calcium is about ten times more abundant than phosphorus in Ryugu samples (Extended Data Table 5), the formation of hydroxyapatite would have entirely consumed phosphorus while the calcium abundance would have remained almost unchanged. Since phosphorus is quite scarce (P/Si = 0.0073 ± 0.0001; Extended Data Table 5) and hydroxyapatite very stable and particularly poorly water soluble, it is unlikely that a substantial part of the phosphorus would have been remobilized in a later ‘alteration’ event to form the HAMP inclusions that have been detected, especially at the low temperatures experienced by Ryugu and its parent body (for example, refs. 6,31,33). Therefore, as explained above, the formation of HAMP grains versus hydroxyapatite is primarily determined by the availability of constitutive ions (for example, ref. 34). The presence of HAMP grains thus translates the competition between the formation of phosphates and that of carbonates, for their coupled role in integrating and thus depleting both Ca and Mg ions (for example, refs. 35–38). In particular, the local closed-system environments that may have been in place on such primitive bodies may have been key to limiting the formation of apatites by depleting calcium in the environment through the formation of carbonates and to favour that of HAMP-rich grains.

The presence of HAMP grains, therefore, puts strong constraints on the sequence of formation of the different constituents and on the evolution of the environment of their parent body, since their earliest formation phases within the protoplanetary disk, possibly from a reservoir similar to that of some comets³⁰,³⁹. Although HAMP grains probably originated from the outer Solar System, their occurrence in Ryugu samples indicates that they remained preserved since their formation, as a key record of the sequence of events that the Ryugu parent bodies experienced, throughout their history. As quoted above, part of the stability of HAMP grains probably originates from the presence of H₂O molecules in their structure. Notably, the preservation of NH₄⁺ ions indicates that HAMP have not suffered major thermal heating since their formation⁴⁰.

Finally, this discovery delivers a critical outcome of biochemical relevance, with respect to the role these grains may have played when they were brought to the inner Solar System together with CHNOS compounds (for example, refs. 4,41–43) and then immersed in the ancient terrestrial water reservoirs (for example, ref. 44). By contrast to apatites, which tend to strongly limit the availability of phosphorus-rich compounds for further chemical reactions once formed (known as the ‘phosphate problem’⁴⁵,⁴⁶), HAMP favours its release by dissolution in liquid water. These minerals would have also displayed a much
greater reactivity than that of phosphates from the apatite group, in particular thanks to the presence of ammonium and of the Mg²⁺ divalent cation⁴⁷,⁴⁸. Moreover, the coupled delivery of soluble P-rich and reduced N-bearing phases through the HAMP grains, together with an organic-rich Ryugu-like matter, might have favoured a rapid reaction chain against the water dilution. It is noticeable that the P/C ratio in Ryugu grains is close to that in biomass (Extended Data Table 5⁴⁹,⁵⁰). They may have offered a pathway towards the formation of organophosphorus compounds, including organophosphates, known to be part of biomolecules such as RNA, DNA and ATP, and phosphorylation reactions (for example, refs. 48,51). In fact, the ability of the struvite analogue to form organophosphates with good yields has been reported by various surveys (for example, refs. 34,51–54). HAMP grains, coupled to the organics present in the same material, formed in the outer protoplanetary disk and preserved till their delivery to terrestrial standing water, would have been essential providers of phosphorous, carbonaceous and nitrogenous compounds to biochemical syntheses.

## Methods

### MicrOmega

The methodology regarding the MicrOmega instrument within the Curation Facility is similar to that presented in refs. 2,3. MicrOmega is mounted in an ultraclean-N₂ purged chamber to prevent H₂O/CO₂ contamination. The instrument is cooled down by being mounted on a copper plate maintained at 10 °C to decrease thermal emission within the instrument and increase the signal-to-noise ratio. To be imaged by MicrOmega, the samples are introduced within a 'sample chamber' part of the main Curation Facility suite¹ separated from the MicrOmega chamber by a NIR-transparent sapphire (Al₂O₃) window. The sample chamber, which has been extensively ultracleaned as the entire facility suite, is permanently flowed with N₂. Each sample is deposited on a dedicated sapphire sample holder set on a polished gold-coated mirror. The sample holder is set on a (x, y, z, θ) moving stage, remotely controlled, enabling to locate the entire surface of the sample within the MicrOmega field of view and to illuminate the grains with different azimuth angles. The MicrOmega instrument sequentially illuminates the sample at different wavelengths with an incidence angle of -35°. For each illuminated wavelength, an image is acquired in a 'nadir' configuration on a two-dimensional mercury-cadmium-telluride (MCT) sensor, cooled down to 110 K with a dedicated cryocooler. A hyperspectral (x, y, λ) cube is built by scanning the different monochromatic channels in the 0.99–3.65 µm wavelength range. Thanks to the use of an acousto-optic tunable filter (AOTF) as a dispersive system, with a full width at half maximum (FWHM) of -20 cm⁻¹, the wavelengths can be selected and repeated in any order with minimum sampling steps of -2 cm⁻¹. For the baselined operations, the typical number of spectral channels per cube varies between -200 and -400. Importantly, as the AOTF is electronically controlled, it offers the capability to measure and subtract 'on-the-fly' the background signal, originating from the thermal emission of the sample, the thermal emission of the instrument, the straylight and the dark current, by successively switching the AOTF on and off. This procedure, baselined for routine operations, makes the instrument insensitive to long-term temperature variations during the observation and significantly enhances the retrieval of the scientific signal detected. Since the dispersive system is part of the illumination path, the thermal background (from both the sample and the instrument) measured by the instrument is integrated over the entire spectral range (and thus does not vary with the wavelength of the illuminating beam). The calibration process and the resulting performances are fully described in ref. 55. The radiometric calibration is evaluated to be better than 20% in absolute value, and -1% in relative value (from one spectral channel to the next). The spectral accuracy is evaluated to be within ±2.5 nm.

First, bulk samples A1–A3 and C1–C3 (ref. 1) were analysed by the suite of instruments installed within the ISAS Curation Facility, including MicrOmega. Then, aggregate samples and individual

(millimetre-sized) grains were extracted from the initial bulk samples and analysed in a similar way. Details about the different samples can be found at the JAXA Data Archives and Transmission System (https://www.darts.isas.jaxa.jp/curation/hayabusa2/).

### Particle extraction and SEM-EDS at the Kochi Institute for Core Sample Research

White particles used in this study were extracted by the Phase 2 Curation team at the Kochi Institute for Core Sample Research, JAMSTEC. The C0209 (5.3 mg) and A0218 (13.1 mg) samples consist of aggregates with a particle size <1 mm. The extraction of the white particle from C0209 was conducted under a pure nitrogen condition in a glove box, but for A0218 it was carried out under the ambient atmospheric condition on a clean bench. The white particles from C0209 and A0218 were placed on a carbon nanotube tape (CNT). They were then subject to imaging and compositional analyses by secondary electron (SE) and back-scattered electron (BSE) microscopy, with a Hitachi High-Tech SU1510 SEM equipped with a Horiba Emax EDS detector. Notably, the EDS detector window prevents the detection of low X-ray energy atoms (for example, N), except when at very large abundance, typically a few tens of wt% (for example, ref. 56 for N, C from CNT).

### XRD

A fraction of the white particle extracted from C0209 was examined by synchrotron X-ray diffraction (SXRD) at the beamline BL 20XU at SPring-8, Japan. XRD patterns were acquired from bulk volume of the sample. The detector (BM AA60, Hamamatsu Photonics) is equipped with a scintillator consisting of a P43 (Gd₂O₃S:Tb) powder screen that is 50 µm thick, the complementary metal oxide semiconductor camera (which has 2,304 × 2,304 pixels (C15440-20UP, Hamamatsu Photonics)) and relay lenses. The pixel size of the detector is 19.05 µm, and the field of view was 39 × 39 mm². An X-ray beam with 30 keV of energy was focused by a Fresnel zone plate. The detector for the XRD mode was placed 110 mm behind the sample, with a 3 mm beam stop just in front of the detector. Diffraction images from 2θ = 1.43° to 18.00° were obtained by the detector. Samples were vertically translated with a certain interval, and half-rotated for each vertical scan step. Diffraction of mineral grains in a horizontal plane can be obtained if the mineral grains meet the Bragg condition in the half rotation. Diffraction images were then integrated into one image for each vertical scan step.

### MIR micro-spectro-imagery

The MIR reflectance analyses have been performed at the SOLEIL facility, France, with an Agilent Cary 670/620 imaging microscope using a Globar source and equipped with a 128 × 128 pixel focal plane array detector sensitive in the spectral range from 2.5 to 12 µm (spectral resolution of 8 cm⁻¹). We used an 15× objective, which gives a pixel size of 5.5 × 5.5 µm² (field of view: 704 × 704 µm²). The radiometric calibration was performed using a reference gold mirror.

### SEM-EDS on C0209 pressed particle

A portion of the white particle mounted on the CNT was removed and pressed into a gold foil following methodology previously used for samples such as interplanetary dust particles (for example, ref. 57). The sample was imaged (SE and BSE) on the Zeiss Crossbeam 550 SEM at the Open University. An EDS map was made of the white particle plus some of the surrounding matrix material. This approach only provides semi-quantitative results, although reproducibility was generally good for O, Mg and P (at a level of a few percent). The EDS detector window prevents the detection of low X-ray energy atoms (for example, N), except when at very large abundance.

### Data availability

Source data are provided with this paper. Infrared spectral data obtained in the ISAS Curation Facility will also be available in the
catalogue of Ryugu samples (https://www.darts.isas.jaxa.jp/curation/hayabusa2/). Other data and images on the Ryugu samples are available at the same address.

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## Acknowledgements

We deeply thank the entire Hayabusa2 team for the opportunity to be part of this outstanding mission. We also thank the Centre National d'Etudes Spatiales (CNES) for its full support. The MIR microspectroscopy measurements were supported by grants from Region Ile-de-France (DIM-ACAV) and SOLEIL. This research was also

supported in part by the JSPS KAKENHI (grant numbers JP18K18795, JP18H04468 and JP23H01238 to M. Ito). Finally, we offer special thanks to B. Gondet, who, although no longer with us, contributed largely to this work.

## Author contributions

D.B., R.B., M.I., I.F., N.T., M.U., A.Y., R.G., T.O., T.U., T.Y., A. Nakato, V.H., J.-P.B., C.P. and F.B. conceived and designed the experiments and the workflow. D.L., C.P., R.B., T.Y., K.H., K.Y., T.L.P.-J., L.R., Y.E., Y.H., K.K., C.L., M.M., A.M., K.N., A. Nakano, A. Nakata, M.N., T. Ojima, L.R., Y.S. and R.T. performed the measurements with MicrOmega. M.O. conducted the sample handling in the glovebox after extraction from the ISAS Curation Facility. M.I. and N.T. performed the SEM/EDS measurements. M.U., A.Y., N.I., N.T. and M.I. performed the SXRD measurements. D.B., R.B. and C.P. performed the MIR micro-spectro-imagery measurements at Soleil Synchrotron. I.F., R.G. and Z.M. prepared the CO209 white particle extract pressed into a gold foil and performed the SEM-EDS measurements. C.P., D.B., J.-P.B., R.B, M.I., I.F., N.T., M.U., A.Y., R.G., D.L., T.L.P.-J., T.J., J.C., V.H., Y.L., F.P. and L.R. contributed to the data processing, analysis and interpretation. C.P., D.B., J.-P.B. and R.B. wrote the draft of the manuscript. All co-authors were involved in the discussions of the results and the finalization of the manuscript.

## Competing interests

The authors declare no competing interests.

## Additional information

Extended data is available for this paper at https://doi.org/10.1038/s41550-024-02366-w.

Correspondence and requests for materials should be addressed to C. Piloget.

Peer review information *Nature Astronomy* thanks Matthew Pasek and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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© The Author(s), under exclusive licence to Springer Nature Limited 2024

<footnote n="1">¹Institut d'Astrophysique Spatiale, Université Paris-Saclay, CNRS, Orsay, France. ²Institut Universitaire de France, Paris, France. ³Kochi Institute for Core Sample Research, JAMSTEC, Kochi, Japan. ⁴National Graduate Institute for Policy Studies, Minato, Japan. ⁵Open University, Walton Hall, Milton Keynes, UK. ⁶Japan Synchrotron Radiation Research Institute, SPring-8, Hyogo, Japan. ⁷National Institute of Polar Research, Tachikawa, Japan. ⁸Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan. ⁹University of Tokyo, Tokyo, Japan. ¹⁰Marine Works Japan Ltd, Yokosuka, Japan. ¹¹School of Earth Sciences, China University of Geosciences, Wuhan, China. ¹²The Graduate University for Advanced Studies (SOKENDAI), Hayama, Japan. ¹³SMIS-SOLEIL, Gif-sur-Yvette, France. ¹⁴Osaka University, Osaka, Japan. ¹⁵Lawrence Livermore National Laboratory, Livermore, CA, USA. ¹⁶Photon Factory/Institute of Materials Science, High Energy Accelerator Research Organization, Tsukuba, Japan. ¹⁷European Space Agency, European Space Astronomy Centre, Madrid, Spain. ¹⁸Kanagawa University, Kanagawa, Japan. ¹⁹Institute for Molecular Science, UVSOR Synchrotron Facility, Okazaki, Japan. ²⁰Centre National d'Etudes Spatiales, Toulouse, France. ²¹Kanagawa Institute of Technology, Atsugi, Japan.</footnote>

<footnote n="22">²²University of Tokyo, Kashiwa, Japan. ²³Nagoya University, Nagoya, Japan. e-mail: cedric.piloget@universite-paris-saclay.fr</footnote>
<figure><img src="image_8.png" /><figcaption>**Extended Data Fig. 1** | IR spectral properties of A0218 extracted grain. (left) Visible image of the grain extracted from A0218 aggregate sample obtained with the visible camera on the Agilent Cary 670/620 imaging microscope</figcaption></figure>

<figure><img src="image_9.png" /></figure>

at SOLEIL Synchrotron facility. (right) MIR reflectance spectra of regions A (phosphate-rich) and B (matrix-rich) shown on the left image. A factor of x2 is applied to spectrum A.
<figure><img src="image_10.png" /></figure>

<figure><img src="image_11.png" /></figure>

**Extended Data Fig. 2** | SEM/EDS analyses of C0209 extracted particle. Top. SEM analyses of C0209 extracted particle. Dots indicate the location of EDS analyses. P/Si atomic ratio highlight the P-rich areas. Bottom. Examples of EDS data obtained C0209 extracted particle. Point #6 shows a P, O and Mg-rich

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

composition (characteristic of HAMP material), while Point #4 shows a typical Ryugu-matrix signature. The C peaks likely originate from the specific analytical protocol used, with grains placed on carbon nanotube tape (see Methods).
<figure><img src="image_13.png" /><figcaption>**Extended Data Fig. 3** | SEM/EDS analyses of A0218 extracted particle. Top. SEM analyses of the A0218 extracted particle. Dots indicate the location of EDS analyses. P/Si atomic ratio highlight the P-rich areas. Bottom. Examples of EDS data obtained for the A0218 extracted particle. Point #14 shows a P, O and Mg-rich</figcaption></figure>

composition (characteristic of HAMP material), while Point #19 shows a typical Ryugu-matrix signature. The C peaks likely originate from the specific analytical protocol used, with grains placed on carbon nanotube tape (see Methods).
<figure><img src="image_14.png" /></figure>

**Extended Data Fig. 4** | SXRD diffraction pattern obtained on a P-rich area of the C0209 extracted particle. Only small peaks from pyrrhotite, pentlandite and magnetite, typically present in matrix material that surrounds the P-rich

areas, can be observed, suggesting the presence of matrix material on the P-rich areas. The absence of other features indicates that the P-rich material is mostly amorphous.
<figure><img src="image_15.png" /></figure>

**Extended Data Fig. 5** | Correlation of 9.5 µm and 6.9 µm spectral features for CO209 extracted particle. BD 9.5 µm vs. BD 6.9 µm from the data displayed in Fig. 2, showing the correlation between both absorption features. Each point in

the graph correspond to a 5 × 5 µm² pixel (thus no binning is applied). Pixels with a reflectance factor at 2.58 µm lower than 0.03 (corresponding to the absence of Ryugu material) have been removed, similar to Fig. 2.
Extended Data Table 1 | Elemental abundances for CO209 and A0218 extracted particles

<table><thead><tr><th></th><th>Na<sub>2</sub>O</th><th>MgO</th><th>Al<sub>2</sub>O<sub>3</sub></th><th>SiO<sub>2</sub></th><th>P<sub>2</sub>O<sub>5</sub></th><th>SO<sub>3</sub></th><th>K<sub>2</sub>O</th><th>CaO</th><th>Cr<sub>2</sub>O<sub>3</sub></th><th>FeO</th><th>Normalized to 100wt%</th></tr></thead><tbody><tr><td colspan="13" style="text-align: left; font-weight: bold;">CO209</td></tr><tr><td colspan="13" style="text-align: left; font-weight: bold;">CO209,0,2,21</td></tr><tr><td>Point#1</td><td>2.02</td><td>27.15</td><td>2.05</td><td>30.15</td><td>14.01</td><td>9.00</td><td>0.14</td><td>0.27</td><td>0.61</td><td>14.60</td><td>100</td></tr><tr><td>Point#2</td><td>1.04</td><td>33.52</td><td>0.30</td><td>2.80</td><td>52.24</td><td>0.72</td><td>B.D.</td><td>0.16</td><td>0.00</td><td>9.22</td><td>100</td></tr><tr><td>Point#3</td><td>2.60</td><td>23.29</td><td>0.98</td><td>24.23</td><td>15.29</td><td>9.35</td><td>0.14</td><td>0.74</td><td>0.73</td><td>22.64</td><td>100</td></tr><tr><td>Point#4</td><td>2.47</td><td>24.33</td><td>1.88</td><td>32.66</td><td>4.67</td><td>11.80</td><td>B.D.</td><td>0.29</td><td>0.36</td><td>21.54</td><td>100</td></tr><tr><td>Point#6</td><td>0.13</td><td>34.33</td><td>0.62</td><td>0.91</td><td>59.73</td><td>0.50</td><td>0.07</td><td>0.07</td><td>B.D.</td><td>3.65</td><td>100</td></tr><tr><td>Point#7</td><td>0.63</td><td>20.95</td><td>2.25</td><td>30.80</td><td>2.25</td><td>17.12</td><td>0.14</td><td>0.27</td><td>0.78</td><td>24.81</td><td>100</td></tr><tr><td>Point#8</td><td>2.33</td><td>29.83</td><td>0.67</td><td>13.37</td><td>38.16</td><td>5.55</td><td>0.18</td><td>0.39</td><td>0.21</td><td>9.30</td><td>100</td></tr><tr><td colspan="13" style="text-align: left; font-weight: bold;">CO209,0,2,22</td></tr><tr><td>Point#9</td><td>1.38</td><td>23.82</td><td>2.58</td><td>35.99</td><td>0.79</td><td>10.12</td><td>B.D.</td><td>0.03</td><td>0.95</td><td>24.35</td><td>100</td></tr><tr><td>Point#10</td><td>1.72</td><td>14.24</td><td>0.86</td><td>19.28</td><td>2.50</td><td>12.83</td><td>B.D.</td><td>0.31</td><td>1.62</td><td>46.64</td><td>100</td></tr><tr><td>Point#11</td><td>1.38</td><td>13.42</td><td>1.87</td><td>6.86</td><td>5.53</td><td>2.70</td><td>0.09</td><td>0.36</td><td>0.00</td><td>67.79</td><td>100</td></tr><tr><td colspan="13" style="text-align: left; font-weight: bold;">A0218</td></tr><tr><td>Point#11</td><td>0.01</td><td>36.70</td><td>B.D.</td><td>0.30</td><td>62.81</td><td>B.D.</td><td>0.07</td><td>0.01</td><td>B.D.</td><td>0.09</td><td>100</td></tr><tr><td>Point#12</td><td>0.03</td><td>34.45</td><td>B.D.</td><td>0.41</td><td>64.56</td><td>0.14</td><td>0.07</td><td>0.04</td><td>0.02</td><td>0.28</td><td>100</td></tr><tr><td>Point#13</td><td>0.05</td><td>28.26</td><td>0.05</td><td>0.65</td><td>70.11</td><td>B.D.</td><td>0.06</td><td>0.02</td><td>0.10</td><td>0.71</td><td>100</td></tr><tr><td>Point#14</td><td>0.10</td><td>34.86</td><td>0.10</td><td>0.45</td><td>64.10</td><td>B.D.</td><td>0.07</td><td>0.07</td><td>B.D.</td><td>0.32</td><td>100</td></tr><tr><td>Point#15</td><td>0.09</td><td>31.65</td><td>0.02</td><td>0.85</td><td>66.56</td><td>0.21</td><td>0.05</td><td>0.00</td><td>0.04</td><td>0.53</td><td>100</td></tr><tr><td>Point#16</td><td>3.12</td><td>25.47</td><td>2.26</td><td>37.98</td><td>0.05</td><td>14.57</td><td>0.14</td><td>0.31</td><td>0.53</td><td>15.56</td><td>100</td></tr><tr><td>Point#17</td><td>1.11</td><td>11.07</td><td>1.20</td><td>27.30</td><td>B.D.</td><td>10.10</td><td>0.21</td><td>0.00</td><td>1.68</td><td>47.33</td><td>100</td></tr><tr><td>Point#18</td><td>0.40</td><td>4.66</td><td>0.74</td><td>15.05</td><td>0.06</td><td>12.26</td><td>0.04</td><td>0.02</td><td>2.63</td><td>64.15</td><td>100</td></tr><tr><td>Point#19</td><td>2.84</td><td>24.03</td><td>2.41</td><td>38.11</td><td>0.15</td><td>14.85</td><td>0.11</td><td>0.02</td><td>0.37</td><td>17.09</td><td>100</td></tr><tr><td>Point#20</td><td>4.61</td><td>22.75</td><td>2.36</td><td>40.52</td><td>B.D.</td><td>11.64</td><td>0.31</td><td>0.07</td><td>0.67</td><td>17.08</td><td>100</td></tr><tr><td>Point#21</td><td>54.13</td><td>6.75</td><td>0.74</td><td>9.90</td><td>0.81</td><td>17.62</td><td>0.24</td><td>3.62</td><td>0.33</td><td>5.85</td><td>100</td></tr></tbody></table>

Elemental abundances, translated into modelled oxides, derived from SEM-EDS analyses on the CO209 and A0218 extracted particles (Extended Data Figs. 2 and 3). Variability of Na₂O values (for example, #21) also reflect µm-scale inhomogeneity in the Na content of the phyllosilicate-rich matrix⁷.

B.D.: below detection limit
Extended Data Table 2 | Atomic ratios for CO209 extracted particle

<table><thead><tr><th>C0209</th><th>Na/Mg</th><th>Al/Mg</th><th>Si/Mg</th><th>P/Mg</th><th>S/Mg</th><th>K/Mg</th><th>Ca/Mg</th><th>Cr/Mg</th><th>Fe/Mg</th><th>P/Si</th></tr></thead><tbody><tr><td>Point#1</td><td>0,0968</td><td>0,0597</td><td>0,7449</td><td>0,293</td><td>0,1669</td><td>0,0044</td><td>0,0071</td><td>0,0119</td><td>0,3017</td><td>0,3934</td></tr><tr><td>Point#2</td><td>0,0404</td><td>0,0071</td><td>0,056</td><td>0,885</td><td>0,0108</td><td>0</td><td>0,0034</td><td>0</td><td>0,1543</td><td>15,7948</td></tr><tr><td>Point#3</td><td>0,1452</td><td>0,0333</td><td>0,6979</td><td>0,3728</td><td>0,2021</td><td>0,0051</td><td>0,0228</td><td>0,0166</td><td>0,5454</td><td>0,5342</td></tr><tr><td>Point#4</td><td>0,132</td><td>0,0611</td><td>0,9005</td><td>0,109</td><td>0,2442</td><td>0</td><td>0,0086</td><td>0,0078</td><td>0,4967</td><td>0,1211</td></tr><tr><td>Point#6</td><td>0,0049</td><td>0,0143</td><td>0,0178</td><td>0,9881</td><td>0,0073</td><td>0,0017</td><td>0,0015</td><td>0</td><td>0,0596</td><td>55,5672</td></tr><tr><td>Point#7</td><td>0,0391</td><td>0,0849</td><td>0,9862</td><td>0,061</td><td>0,4114</td><td>0,0057</td><td>0,0093</td><td>0,0197</td><td>0,6644</td><td>0,0618</td></tr><tr><td>Point#8</td><td>0,1016</td><td>0,0178</td><td>0,3007</td><td>0,7265</td><td>0,0937</td><td>0,0052</td><td>0,0094</td><td>0,0037</td><td>0,1749</td><td>2,4163</td></tr><tr><td>Point#9</td><td>0,0753</td><td>0,0856</td><td>1,0135</td><td>0,0188</td><td>0,2139</td><td>0</td><td>0,0009</td><td>0,0212</td><td>0,5735</td><td>0,0186</td></tr><tr><td>Point#10</td><td>0,1571</td><td>0,0477</td><td>0,9082</td><td>0,0997</td><td>0,4536</td><td>0</td><td>0,0156</td><td>0,0603</td><td>1,8375</td><td>0,1098</td></tr><tr><td>Point#11</td><td>0,1337</td><td>0,1102</td><td>0,3429</td><td>0,234</td><td>0,1013</td><td>0,0057</td><td>0,0193</td><td>0</td><td>2,834</td><td>0,6824</td></tr></tbody></table>

Atomic ratios derived from SEM-EDS analyses performed on the C0209 extracted grain (Extended Data Fig. 2). The above table emphasizes the difference in composition of the HAMP (P-rich grains), point #6 in particular, with respect to the Si-rich matrix spots. Noticeably, the P-rich grains are Mg-rich, and almost Ca-free, which excludes apatite as a candidate.
Extended Data Table 3 | Atomic ratios for A0218 extracted particle

<table><thead><tr><th>A0218</th><th>Na/Mg</th><th>Al/Mg</th><th>Si/Mg</th><th>P/Mg</th><th>S/Mg</th><th>K/Mg</th><th>Ca/Mg</th><th>Cr/Mg</th><th>Fe/Mg</th><th>P/Si</th></tr></thead><tbody><tr><td>Point#11</td><td>0,0004</td><td>0</td><td>0,0055</td><td>0,9719</td><td>0</td><td>0,0016</td><td>0,0002</td><td>0</td><td>0,0014</td><td>177,2455</td></tr><tr><td>Point#12</td><td>0,0011</td><td>0</td><td>0,008</td><td>1,0642</td><td>0,002</td><td>0,0017</td><td>0,0008</td><td>0,0003</td><td>0,0046</td><td>133,3053</td></tr><tr><td>Point#13</td><td>0,0023</td><td>0,0014</td><td>0,0154</td><td>1,4089</td><td>0</td><td>0,0018</td><td>0,0005</td><td>0,0019</td><td>0,0141</td><td>91,3133</td></tr><tr><td>Point#14</td><td>0,0037</td><td>0,0023</td><td>0,0087</td><td>1,0442</td><td>0</td><td>0</td><td>0,0014</td><td>0</td><td>0,0052</td><td>120,5905</td></tr><tr><td>Point#15</td><td>0,0037</td><td>0,0005</td><td>0,018</td><td>1,1943</td><td>0,0033</td><td>0,0014</td><td>0</td><td>0,0007</td><td>0,0094</td><td>66,2921</td></tr><tr><td>Point#16</td><td>0,1593</td><td>0,0702</td><td>1,0003</td><td>0,0011</td><td>0,288</td><td>0,0047</td><td>0,0087</td><td>0,011</td><td>0,3427</td><td>0,0011</td></tr><tr><td>Point#17</td><td>0,1304</td><td>0,0857</td><td>1,6543</td><td>0</td><td>0,4593</td><td>0,0162</td><td>0</td><td>0,0805</td><td>2,3987</td><td>0</td></tr><tr><td>Point#18</td><td>0,1116</td><td>0,1255</td><td>2,1664</td><td>0,0073</td><td>1,3244</td><td>0,0073</td><td>0,0031</td><td>0,2993</td><td>7,7232</td><td>0,0034</td></tr><tr><td>Point#19</td><td>0,1537</td><td>0,0793</td><td>1,0639</td><td>0,0035</td><td>0,3111</td><td>0,0039</td><td>0,0006</td><td>0,0082</td><td>0,399</td><td>0,0033</td></tr><tr><td>Point#20</td><td>0,2635</td><td>0,082</td><td>1,1948</td><td>0</td><td>0,2576</td><td>0,0117</td><td>0,0022</td><td>0,0156</td><td>0,4212</td><td>0</td></tr><tr><td>Point#21</td><td>10,4296</td><td>0,0867</td><td>0,9838</td><td>0,0681</td><td>1,3141</td><td>0,0304</td><td>0,3855</td><td>0,0259</td><td>0,4862</td><td>0,0693</td></tr></tbody></table>

Atomic ratios derived from SEM-EDS analyses performed on the A0218 extracted grain (Extended Data Fig. 3). The above table emphasizes the difference in composition of the HAMP (P-rich grains), points #11-15, with respect to the Si-rich matrix spots. Similar to CO209, the P-rich grains are Mg-rich, and almost Ca-free, which excludes apatite as a candidate.
Extended Data Table 4 | Solubility of various carbonates and phosphates

<table><thead><tr><th>Mineral formula</th><th>Name</th><th>pKs (at 298K)</th><th>Ref.</th><th>Calculated solubility in mol/L (at 298K)</th><th>Deduced phosphate ion concentration at equilibrium in mol/L (at 298 K)</th></tr></thead><tbody><tr><td>Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH)</td><td>hydroxyapatite</td><td>54.45</td><td>[59]</td><td>2.53 × 10<sup>-7</sup></td><td>7.58 × 10<sup>-7</sup></td></tr><tr><td>CaMg(CO<sub>3</sub>)<sub>2</sub></td><td>dolomite</td><td>17.09</td><td>[59]</td><td>3.78 × 10<sup>-5</sup></td><td>---</td></tr><tr><td>NH<sub>4</sub>MgPO<sub>4</sub>·6H<sub>2</sub>O</td><td>struvite</td><td>13.17</td><td>[59] and references therein</td><td>4.07 × 10<sup>-5</sup></td><td>4.07 × 10<sup>-5</sup></td></tr><tr><td>FeCO<sub>3</sub></td><td>siderite</td><td>10.90</td><td>[60]</td><td>3.55 × 10<sup>-6</sup></td><td>---</td></tr><tr><td>CaCO<sub>3</sub></td><td>calcite</td><td>8.48</td><td>[59]</td><td>5.75 × 10<sup>-5</sup></td><td>---</td></tr><tr><td>CaCO<sub>3</sub></td><td>aragonite</td><td>8.34</td><td>[59]</td><td>6.76 × 10<sup>-5</sup></td><td>---</td></tr><tr><td>MgCO<sub>3</sub></td><td>magnesite</td><td>7.80</td><td>[61]</td><td>1.26 × 10<sup>-4</sup></td><td>---</td></tr></tbody></table>

Solubility product constants and solubilities (in mol/L) deduced at 298K.
Extended Data Table 5 | Elemental abundances relative to Si in CI chondrites and Ryugu samples

<table><thead><tr><th>Atomic number</th><th>Element</th><th>E/Si in Cls (calculated from [58])</th><th>E/Si uncertainty (calculated from [58])</th><th>E/Si in Ryugu samples (calculated from XRF analyses in [31])</th><th>E/Si uncertainty (calculated from XRF analyses in [31])</th></tr></thead><tbody><tr><td>6</td><td>C</td><td>0.8937</td><td>0.2415</td><td>0.8248</td><td>0.0177</td></tr><tr><td>8</td><td>O</td><td>7.3679</td><td>0.8171</td><td>5.3134</td><td>0.0667</td></tr><tr><td>11</td><td>Na</td><td>0.0576</td><td>0.0095</td><td>0.0741</td><td>0.0018</td></tr><tr><td>12</td><td>Mg</td><td>1.0303</td><td>0.1122</td><td>1.1478</td><td>0.0120</td></tr><tr><td>13</td><td>Al</td><td>0.0806</td><td>0.0112</td><td>0.0824</td><td>0.0014</td></tr><tr><td>14</td><td>Si</td><td>1.0000</td><td>0.1337</td><td>1.0000</td><td></td></tr><tr><td>15</td><td>P</td><td>0.0082</td><td>0.0016</td><td>0.0073</td><td>0.0001</td></tr><tr><td>16</td><td>S</td><td>0.4353</td><td>0.0648</td><td>0.3355</td><td>0.0040</td></tr><tr><td>17</td><td>Cl</td><td>0.0053</td><td>0.0024</td><td>0.0048</td><td>0.0002</td></tr><tr><td>19</td><td>K</td><td>0.0036</td><td>0.0006</td><td>0.0032</td><td>0.0001</td></tr><tr><td>20</td><td>Ca</td><td>0.0574</td><td>0.0084</td><td>0.0780</td><td>0.0014</td></tr><tr><td>22</td><td>Ti</td><td>0.0024</td><td>0.0003</td><td>0.0022</td><td>0.0002</td></tr><tr><td>24</td><td>Cr</td><td>0.0130</td><td>0.0019</td><td>0.0143</td><td>0.0004</td></tr><tr><td>25</td><td>Mn</td><td>0.0090</td><td>0.0014</td><td>0.0101</td><td>0.0003</td></tr><tr><td>26</td><td>Fe</td><td>0.8617</td><td>0.1179</td><td>0.7220</td><td>0.0092</td></tr><tr><td>27</td><td>Co</td><td>0.0022</td><td>0.0003</td><td>0.0022</td><td>0.0001</td></tr><tr><td>28</td><td>Ni</td><td>0.0484</td><td>0.0063</td><td>0.0420</td><td>0.0004</td></tr></tbody></table>

Calcium is about 10 times more abundant than phosphorus in Ryugu samples (about 7 times in CI chondrites).