Pułtusk H5 Chondrite—A Compilation of Chemical, Physical, and Thermophysical Data

Abstract

The Pułtusk meteorite, classified as an H5 ordinary chondrite, is one of the best documented Polish falls, yet some important data on its physical and thermophysical properties remain limited. This study provides new measurements and derived parameters of its physical and thermophysical properties that complement existing datasets for the Pułtusk meteorite and H chondrites in two important ways. Firstly, they cover a temperature range previously not explored. Secondly, using techniques generally applied in geology to validate the novel techniques developed recently, bulk and grain densities, porosity, and specific heat capacity were determined using the Archimedean method and differential scanning calorimetry, supported by bulk chemical analyses performed by ICP-MS and ICP-ES. The chemical composition of Pułtusk closely matches that of average H chondrites, though Fe and Ni contents are about 15–20% lower, likely due to weathering effects. Measured bulk density, grain density, and porosity are 3.30 g/cm³, 3.41 g/cm³, and 3.22%, respectively. The specific heat capacity increases from 564 to 1147 J/(kg·K) between 223 and 773 K, with 699 J/(kg·K) at 300 K. Derived thermophysical parameters include thermal conductivity, thermal diffusivity, and thermal inertia at 200 K, 300 K, and low pressure, and in ambient air. These results are consistent with previous data for H chondrites and confirm Pułtusk as a representative sample of this group. The new dataset can enhance the accuracy of models describing the Yarkovsky effect, meteoroid atmospheric entry, and the thermal evolution of ordinary chondrite parent bodies.

1. Introduction

The Pułtusk meteorite is an ordinary chondrite (OC), classified as H5 [1]. The H group of OCs is characterized by a higher amount of metals in the form of FeNi alloys; petrographic type 5 indicates some thermal metamorphic changes in the rock. It is one of the best known Polish meteorites, distributed worldwide; nevertheless, its physical and thermophysical characterization has not yet been completed. The meteorite shower fell over northeast Poland in 1868. The first samples of this meteorite were collected directly after the fall and distributed among many prime collections such as the National History Museum in London (9095 g), the Earth Museum of the Polish Academy of Science in Warsaw (8100 g), and Natur Historisches Museum in Berlin (8070 g) [2]. It is estimated that at least 250 kg of chondritic rock reached the ground [1]. However, an alternative calculation suggests that as much as 2080 kg² of chondritic rock originated from the S-type asteroid [3], which is the parent body of H chondrites: e.g., asteroids 6 Hebe [4], 148 Galia, 57 Mnemosyne, 23 Thalia, 14 Irene, 5 Astraea [5] or 3 Juno, and 25 Phocaea [6] as well as asteroid families, e.g., 808 Merxia, 847 Agnia, and 158 Koronis [5]. The strewn field of this meteorite is still searched by meteorite collectors and a few specimens of Pułtusk fall are found every year. The specimen used for this research was found 147 years after its fall. It was donated in order to complement existing datasets of chemical, physical, and thermophysical properties.

The aforementioned facts make Pułtusk one of the best studied Polish meteorites as its samples are relatively easy to obtain from museum collections in many countries. Numerous examinations, e.g., [7,8,9,10,11,12,13,14,15,16,17] on Pułtusk, have been performed on samples with sizes from µg up to 100 g, which could provide a good approximation of the thermal and impact history of the parent body. However, a comprehensive study of the physical and thermophysical properties of this meteorite is still missing. The authors decided to fill this gap by preparing this report.

Determining the physical and thermophysical characteristics of meteorites is fundamental for understanding the processes of asteroid formation and evolution. These properties play a key role in modeling the Yarkovsky effect [18,19,20], which affects the rotation and orbital motion of asteroids, as well as in predicting meteoroid behavior during atmospheric entry [21,22,23], and also in the design of spacecraft and exploration missions. Thermophysical parameters are particularly important for simulating the cooling history of parent bodies following accretion and for assessing heat transfer resulting from the decay of short-lived isotopes [24,25,26]. Furthermore, knowledge of these properties provides valuable insights into the internal structure of asteroids and allows for predictions of their future evolution.

The bulk density, grain density, and porosity of Pułtusk have been determined by different researchers [27,28,29,30,31,32,33]. Thermal conductivity was measured by Opeil et al. [34]. Values of the heat capacity of this meteorite at low temperature were obtained by Consolmagno et al. [35] and Macke et al. [36]. Compressive strength was determined by Medvedev et al. [17] and Kimberley and Ramesh [37], and tensile strength by Medvedev et al. [17] and Svetsov et al. [38], and the Young’s modulus value for this particular chondrite can be found in the work of Flynn et al. [39]. The values of volumetric heat capacity and mean atomic weight as well as mean atom-molar heat capacity of Pułtusk were calculated by Szurgot [40,41].

The aim of this study was to determine the physical and thermophysical properties of the Pułtusk meteorite, extending and complementing the existing dataset for H chondrites with values derived for different temperatures (200 K and 300 K) and pressures (low pressure and ambient air). Since high-temperature data are essential for modeling the evolution of asteroid interiors in the past and for modeling the early evolution of major planets whose initial composition might be similar to asteroid material, in this study the specific heat capacity values of Pułtusk were measured over a broad temperature range (223–773 K) for the first time. Because the bulk chemical composition of the Pułtusk chondrite has not yet been determined, and no published data are available, it was necessary to analyze the meteorite in this regard prior to evaluating its physical and thermophysical properties. This step was essential to verify whether the composition of the Pułtusk specimen corresponds to the average composition of H chondrites; otherwise, the data obtained for this particular specimen might not be representative of the typical rocks from the parent asteroid, i.e., the H chondrite parent body. The chemical composition of the main minerals constituting the Pułtusk specimen characterizes very well the H group of chondrites (for comparison, check the data in Przylibski and Łuszczek [42]).

2. Materials and Methods

The Pułtusk specimen used for this examination was found by Piotr Kuś 147 years after its fall (on 23 November 2015); it is presented in Figure 1. Piotr Kuś discovered two matching fragments of Pułtusk fall and donated a piece of the right specimen visible in Figure 1, top left panel, for this research. Both fragments of the meteorite are in a private collection of the finder. The mineralogical and petrological examination of this Pułtusk specimen was the aim of another study [42].

The Pułtusk sample shows weathering in terrestrial conditions and can be classified as W2 [42,43]. This weathering grade exhibits moderate oxidation of metal and sulfide, with about 20–60% of them replaced by oxidation products. This was confirmed by EPM analysis and microscopic observations in reflected light [42]. The products of weathering of FeNi alloy grains are iron oxides and hydroxides visible both on the BSE images (Figure 1, bottom panels) and in the microscopic view (Figure 1, top right panel).

From the Pułtusk chondrite specimen intended for research, ca. 12 g was cut off and crushed in a jaw crusher and ground in a ball mill in order to homogenize the composition. Then 10.87 g of the prepared sample was examined in Acme Analytical Laboratories Ltd. in Canada for commercial bulk chemical composition analysis. The concentrations of 59 elements were measured using the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) technique. Nickel (Ni) was analyzed separately by Inductively Coupled Plasma Emission Spectroscopy (ICP-ES), as its concentration exceeded the detection limit of the ICP-MS method. Previous experience indicates that the abundance of Zr, Hf, and Y in the samples is always higher than in reality due to contamination by wear from the components of the crusher and ball mill used to prepare the sample in our laboratory in this way.

Bulk density, porosity, and grain density were measured on samples with masses of 0.31 and 0.17 g, while heat capacity was measured on a 22 mg sample. Generally, the methodology of physical and thermophysical measurements was the same as described in the paper by Szurgot et al. [44].

The bulk density, grain density, and porosity of the samples were evaluated using the conventional Archimedean technique. The bulk density (ρ_b) was obtained from the following equation:

$${\rho }_b={\displaystyle \frac{W_{air}}{W_{air}-W_{propanol}}}\times {\rho }_{propanol}$$

(1)

where W_air is the specimen’s mass measured in air, W_propanol represents its apparent mass when suspended in isopropanol, and ρ_propanol denotes the density of isopropanol (785 kg/m³). The relative uncertainty of this determination is approximately 2–3%.

Porosity, defined as the ratio of the volume of void spaces between grains to the total rock volume, was determined by comparing the mass of the dry sample with that of the same sample after saturation with isopropanol. The porosity P(%) was computed according to Equation (2):

$$P\left(\%\right)={\displaystyle \frac{V_p}{V_m}}={\displaystyle \frac{m_p}{m_m}}\times {\displaystyle \frac{{\rho }_b}{{\rho }_{propanol}}}$$

(2)

where V_p is the volume of isopropanol contained in the pore spaces, V_m is the total sample volume, m_p is the mass of the absorbed isopropanol, m_m is the mass of the dry meteorite, ρ_b is the bulk density, and ρ_propanol is the density of isopropanol at ambient conditions (785 kg/m³). The estimated uncertainty of porosity measurements is around 7%.

The grain density (ρ_g) was then calculated from the following relationship:

$${\rho }_g={\displaystyle \frac{{\rho }_b}{1-P}}$$

(3)

where ρ_b is the bulk density and P is porosity.

The specific heat capacity (Cp) was measured using a differential scanning calorimeter (DSC) model Q200 (TA Instruments, New Castle, DE, USA). Prior to the measurements, the DSC was calibrated for both temperature and heat flow. Indium (melting point 156.6 °C) was used for temperature calibration, while a synthetic sapphire standard, with a well-known Cp over a wide temperature range, was used for heat flow calibration. The heat capacity of the Pułtusk meteorite sample was calculated according to Equation (4):

$$Cp={Cp}_{sp}\times {\displaystyle \frac{H}{H_{sp}}}\times {\displaystyle \frac{m_{sp}}{m_m}}$$

(4)

where Cp_sp represents the specific heat capacity of the sapphire standard at a given temperature, m_sp is the mass of the sapphire standard, H is the heat flow (mW) recorded for the meteorite sample, and H_sp denotes the heat flow of the sapphire. The Pułtusk sample, weighing approximately the same as the sapphire reference (about 23 mg), was enclosed in an aluminum pan and analyzed over a temperature range from −50 °C to 500 °C, using a heating rate of 20 °C per minute under a nitrogen atmosphere (flow rate: 50 mL/min). The relative uncertainty in the Cp determination for the Pułtusk sample was estimated to be 3–4% [44,45].

3. Results and Discussion

3.1. Bulk Chemical Composition

In order to check whether the examined specimen of the Pułtusk meteorite is a good representative of H chondrites, its bulk chemical composition data were compared with the average for this group (Figure 2,

Table 1. Abundance of selected elements [wt%] and atomic ratios of selected elements composing the examined Pułtusk meteorite in comparison with average abundances typical for H, L, and LL groups of ordinary chondrites and CI chondrites (according to Hutchison [48]). CI chondrite composition represents the average composition of matter in the Solar System.

Element	H	L	LL	Pułtusk	CI
Si	16.9	18.5	18.9	17.5	10.5
Ti	0.06	0.063	0.062	0.06	0.042
Al	1.13	1.22	1.19	1.13	0.86
Cr	0.366	0.388	0.374	0.392	0.265
Fe	27.5	21.5	18.5	23.5	18.2
Mn	0.232	0.257	0.262	0.25	0.19
Mg	14	14.9	15.3	13.47	9.7
Ca	1.25	1.31	1.3	1.22	0.92
Na	0.64	0.7	0.7	0.56	0.49
K	0.078	0.083	0.079	0.07	0.056
P	0.108	0.095	0.085	0.13	0.102
Ni	1.6	1.2	1.02	1.344	1.07
Co	0.081	0.059	0.049	0.072	0.051
S	2	2.2	2.3	1.67	5.9
C	0.11	0.09	0.12	0.27	3.2
Au	215	162	140	226.2	144
Atomic ratios	H	L	LL	Pułtusk	CI
Mg/Si	0.957	0.931	0.935	0.887	1.068
Al/Six104	696	686	655	672	853
Ca/Six104	518	496	482	486	614
Fe/Six104	8184	5845	4923	6740	8717
Ca/Al	0.74	0.72	0.74	0.72	0.72
Ni/Six104	453	310	258	367	488
CI-normalized atomic ratio	H	L	LL	Pułtusk	CI
Mg/Si	0.90	0.87	0.88	0.83	1
Al/Si	0.82	0.81	0.77	0.79	1
Fe/Si	0.94	0.67	0.56	0.77	1

and Table 2) as well as with the composition of 50 H chondrites (Figure 3). Moreover, Table 1 shows abundances of selected elements in Pułtusk and in all ordinary chondrite groups (H, L, LL) as well as the atomic ratio of selected elements used to distinguish different groups of chondrites. Generally, the content of most elements mentioned in Table 1 in Pułtusk fits relatively well with the H group. Only the abundance of Fe, Ni, and S is ca. 15% lower, while the abundance of P is approximately higher by ca. 20% than the average content of these elements in H chondrites. The analyzed Pułtusk sample contains also almost 2.5 times more C than a typical H chondrite. However, its content is still one order of magnitude lower than in CI carbonaceous chondrites (Table 1). The ratios of selected elements in Pułtusk listed in Table 1 are characteristic of H chondrites, except for Fe/Si and Ni/Si, which are both almost 20% lower. This fact may be (1) a characteristic feature of this meteorite or (2) caused by generally lower content of FeNi alloy grains in the sample used for bulk chemical analysis, or (3) it may reflect weathering of the meteorite in terrestrial conditions. However, Krzesińska [46], using high-resolution X-ray tomography, determined the metal volume content in Pułtusk to be 7.1 vol%. This value is 1 vol% lower than the H chondrite average (8 vol%, Grady et al. [47]), which might suggest generally lower metallic grain content in Pułtusk specimens.

The aforementioned lower Fe and Ni content in Pułtusk is also visible in Figure 2 (14% and 21% lower than in H chondrites, respectively). The abundances of other main elements in Pułtusk follow the pattern typical of H chondrites: as their abundances normalized to H chondrites are close to one, they are visible as a flat line in Figure 2. The content of most REEs (Rare Earth Elements) is higher in Pułtusk than in H chondrites. The greatest enrichment in this meteorite is visible for La (almost six times) as well as Sc and Ce (almost two times). The abundances of Sm, Gd, Er, Tm, and Yb vary by approximately 10% in comparison with the H group. The reason why the light REEs (e.g., Sc, La, Ce) are enriched in Pułtusk relative to average H chondrites is probably the higher phosphate content than in the other samples. Mason and Graham [49] identified phosphates as hosting essentially all LREEs (La to Sm) and half of the HREEs (Gd to Yb). This statement can be supported by the ca. 20% higher P content in Pułtusk in comparison with H chondrites. For other analyzed elements, Ba and Nb are enriched in Pułtusk (ca. 80% and 25%, respectively), while Co, Ga, Rb, Se, Zn, and As are depleted when compared with the average H chondrite (ca. 13%, 23%, 24%, 17%, 70%, and 40%, respectively) (Figure 2, Table 2).

Figure 2. Abundances of analyzed elements in the Pułtusk chondrite normalized to H chondrites in comparison with the abundances of these elements in CI chondrites (according to McSween and Huss [50]).

Figure 2. Abundances of analyzed elements in the Pułtusk chondrite normalized to H chondrites in comparison with the abundances of these elements in CI chondrites (according to McSween and Huss [50]).

Table 2. Abundance of selected elements [ppm] analyzed in the Pułtusk chondrite in comparison with the average abundance [50] and the range of abundance in H chondrites [51].

Element	Pułtusk	Average H	Range H	Element	Pułtusk	Average H	Range H
Si	175,400	171,000	82,000–235,000	Pb	0.2	0.24	0.008–2.28
Al	11,300	10,600	690–11,100	Zn	14	47	0.54–540
Fe	235,000	272,000	42,000–912,000	As	1.3	2.2	0.078–15.1
Mg	134,700	141,000	4600–213,000	Cd	<0.1	<0.01	0.000038–1.24
Ca	12,200	12,200	4100–127,000	Sb	<0.1	0.066	0.0015–0.78
Na	5600	6110	40–29,400	Bi	<0.1	<0.01	0.00016–0.907
K	740	780	100–4700	Ag	<0.1	0.045	0.0032–1.87
Ti	600	630	100–4700	Hg	<0.01	bd	0.19–1.93
P	1300	1200	100–2400	Tl	<0.1	<0.001	0.00004–0.361
Mn	2500	2340	30–5800	Se	6.6	8	0.56–42.5
Cr	3920	3500	30–37,100	Zr *	215.7	7.3	3.09–10.00
Ni	13,440	17,100	100–130,000	Au	0.2262	0.22	0.00213–1.8
Ba	8	4.4	0.13–26.50	Sc	14	7.8	0.04–13.8
Be	<1	0.03	0.03–0.39	Y *	15.1	2	0.74–6.80
Co	718.4	830	25.20–5000.00	La	1.8	0.301	0.087–7.68
Cs	<0.1	<0.2	0.001–2.16	Ce	1.3	0.763	0.45–13.8
Ga	4.6	6	0.58–37.30	Pr	0.16	0.12	0.05–0.4
Hf *	4.9	0.15	0.10–0.38	Nd	0.8	0.581	0.24–1.22
Nb	0.5	0.4	0.20–0.46	Sm	0.21	0.194	0.068–0.73
Rb	1.7	2.3	0.51–86.80	Eu	0.09	0.074	0.055–0.15
Sn	<1	0.35	0.103–2.3	Gd	0.29	0.275	0.1–0.457
Sr	9.6	8.8	8.00–938.00	Tb	0.06	0.049	0.02–0.091
Ta	<0.1	0.021	0.02–0.05	Dy	0.37	0.305	0.12–0.568
Th	<0.2	0.038	0.02–0.285	Ho	0.09	0.074	0.03–0.12
U	<0.1	0.013	0.01–2.44	Er	0.23	0.213	0.07–0.592
V	81	73	2.30–91.10	Tm	0.03	0.033	0.01–0.045
W	<0.5	0.164	0.16–0.87	Yb	0.23	0.203	0.03–0.345
Mo	1.3	1.4	1.24–4.88	Lu	0.04	0.033	0.008–0.068
Cu	94.3	94	48–759	Pb	0.2	0.24	0.008–2.28

* The elements marked with an asterix are likely to have elevated concentrations due to the admixture (contamination) of abrasive material from a crusher and a ball mill used to prepare the sample for ICP-MS analysis.

Table 2. Abundance of selected elements [ppm] analyzed in the Pułtusk chondrite in comparison with the average abundance [50] and the range of abundance in H chondrites [51].

Element	Pułtusk	Average H	Range H	Element	Pułtusk	Average H	Range H
Si	175,400	171,000	82,000–235,000	Pb	0.2	0.24	0.008–2.28
Al	11,300	10,600	690–11,100	Zn	14	47	0.54–540
Fe	235,000	272,000	42,000–912,000	As	1.3	2.2	0.078–15.1
Mg	134,700	141,000	4600–213,000	Cd	<0.1	<0.01	0.000038–1.24
Ca	12,200	12,200	4100–127,000	Sb	<0.1	0.066	0.0015–0.78
Na	5600	6110	40–29,400	Bi	<0.1	<0.01	0.00016–0.907
K	740	780	100–4700	Ag	<0.1	0.045	0.0032–1.87
Ti	600	630	100–4700	Hg	<0.01	bd	0.19–1.93
P	1300	1200	100–2400	Tl	<0.1	<0.001	0.00004–0.361
Mn	2500	2340	30–5800	Se	6.6	8	0.56–42.5
Cr	3920	3500	30–37,100	Zr *	215.7	7.3	3.09–10.00
Ni	13,440	17,100	100–130,000	Au	0.2262	0.22	0.00213–1.8
Ba	8	4.4	0.13–26.50	Sc	14	7.8	0.04–13.8
Be	<1	0.03	0.03–0.39	Y *	15.1	2	0.74–6.80
Co	718.4	830	25.20–5000.00	La	1.8	0.301	0.087–7.68
Cs	<0.1	<0.2	0.001–2.16	Ce	1.3	0.763	0.45–13.8
Ga	4.6	6	0.58–37.30	Pr	0.16	0.12	0.05–0.4
Hf *	4.9	0.15	0.10–0.38	Nd	0.8	0.581	0.24–1.22
Nb	0.5	0.4	0.20–0.46	Sm	0.21	0.194	0.068–0.73
Rb	1.7	2.3	0.51–86.80	Eu	0.09	0.074	0.055–0.15
Sn	<1	0.35	0.103–2.3	Gd	0.29	0.275	0.1–0.457
Sr	9.6	8.8	8.00–938.00	Tb	0.06	0.049	0.02–0.091
Ta	<0.1	0.021	0.02–0.05	Dy	0.37	0.305	0.12–0.568
Th	<0.2	0.038	0.02–0.285	Ho	0.09	0.074	0.03–0.12
U	<0.1	0.013	0.01–2.44	Er	0.23	0.213	0.07–0.592
V	81	73	2.30–91.10	Tm	0.03	0.033	0.01–0.045
W	<0.5	0.164	0.16–0.87	Yb	0.23	0.203	0.03–0.345
Mo	1.3	1.4	1.24–4.88	Lu	0.04	0.033	0.008–0.068
Cu	94.3	94	48–759	Pb	0.2	0.24	0.008–2.28

* The elements marked with an asterix are likely to have elevated concentrations due to the admixture (contamination) of abrasive material from a crusher and a ball mill used to prepare the sample for ICP-MS analysis.

Figure 3. Comparison of the abundance of elements in the Pułtusk chondrite examined in this study and in other H chondrites (data for the top and middle panels from Jarosewich [52]; those for the bottom panel from Morgan et al. [53]). The average abundance of each particular element in the H chondrite population considered is specified in the legend and indicated in the chart as a horizontal line of its respective color. Data for Pułtusk are indicated by the black arrows. (Top panel) main components. (Middle panel) selected elements. (Bottom panel) trace elements. Note that the middle and bottom panels both have a logarithmic scale.

Figure 3. Comparison of the abundance of elements in the Pułtusk chondrite examined in this study and in other H chondrites (data for the top and middle panels from Jarosewich [52]; those for the bottom panel from Morgan et al. [53]). The average abundance of each particular element in the H chondrite population considered is specified in the legend and indicated in the chart as a horizontal line of its respective color. Data for Pułtusk are indicated by the black arrows. (Top panel) main components. (Middle panel) selected elements. (Bottom panel) trace elements. Note that the middle and bottom panels both have a logarithmic scale.

The content of Be, Cs, Sn, Ta, Th, U, W, Cd, Sb, Bi, Ag, Hg, and Tl was below the detection limit of ICP MS as shown for each element in Table 2, but nevertheless the obtained data are in agreement with the average H chondrite composition.

Comparing data on the determined bulk chemical composition of the Pułtusk specimen with a set of 50 H chondrites (Figure 3) shows that there are five H chondrites (Clovis (H3), Suwahib (Buwah) (H3), Hammond Downs (H4), ALHA 76008 (H6), and Mills (H6)) with lower Fe content similar to Pułtusk, and for similar lower content of Ni there are four H chondrites (Study Butte (H3), Sawahib (Buwah) (H3), Willaroy (H3), and Oro Grande (H5)). Furthermore, Beaver Creek (H4) has an even lower abundance of Zn than Pułtusk. The contents of other elements, presented in Figure 3, in Pułtusk fit very well with the averages of these H chondrite sets.

All analyzed elements in Pułtusk are within the range of their abundances in H chondrites (Table 2). Only the Al and Sc content is marginally higher than this range; however, when examining the data in Table 1, the Al content in Pułtusk fits perfectly with the H chondrite average. The lower by 15% abundance of Fe and by 15–21% of Ni (depending on the average literature data taken for comparison as the H chondrite average [48,50]) can slightly influence the values of physical and thermophysical properties. In this respect, the variations in the content of other elements can be neglected as their contents are in ppm. Our rough estimations based on the geometric mean model of Soini et al. [54] show that 2.8% lower content of FeNi in the sample can cause the thermal conductivity to decrease by approximately 0.3 W/(m·K) in ambient air (considering porosity at the level measured in our Pułtusk sample).

3.2. Physical Properties

Bulk density was determined for two samples with masses of 0.31 g and 0.17 g by applying the Archimedean method (using Equation (1)), yielding ρ_b = 3.32 g/cm³ and ρ_b = 3.28 g/cm³, respectively. Since the obtained values are very close to each other, the mean bulk density of the Pułtusk samples measured in the current study is ρ_b = 3.30 g/cm³. Porosity values calculated using Equation (2) were 3.19% and 3.25%, so the mean porosity of Pułtusk is 3.22%. The mean value of grain density obtained using Equation (3) is ρ_g = 3.41 g/cm³ (3.43 and 3.38 g/cm³, respectively). The results of this work are in good agreement with data obtained by Macke [31], who examined more than 20 Pułtusk specimens (

Table 3. Comparison of selected physical properties of Pułtusk (H5) meteorite with Košice (H5) [56] and other H chondrites (n—number of samples measured).

Meteorite(s)	Bulk Density [g/cm3]	Grain Density [g/cm3]	Porosity [%]	n	Notes
Pułtusk (H5)	3.30	3.41	3.22	2	Current study, Archimedean method
Pułtusk (H5)	3.44	3.72	7.4	23	[31]
	(3.22–3.77)	(3.54–3.89)	(0.3–12.1)		Helium pycnometry, glass bead method
Pułtusk (H5)	3.57			1	[33]
	3.60			1	3D laser scanning
Pułtusk (H5)	3.47			2	[28] Glass bead method, Archimedean method
Pułtusk (H5)	3.60			1	[30]
	3.56			1	Glass bead method
Pułtusk (H5)	3.36–3.8	3.55–3.82	0.17–11.97	11	[29] Glass bead method, helium pycnometry
Košice (H5)	3.0–3.6	3.7–4.3	4–20	67	[56] Glass bead method, helium pycnometry
H falls	3.35 ± 0.01	3.71 ± 0.01	9.5 ± 0.04	207 (116) a	[31] Helium pycnometry, glass bead method
	(2.51–3.77)	(3.18–4.14)	(0–26.6)
H finds	3.43	3.51	2.8	79 (63) b
	(2.86–4.21)	(3.19–3.79)	(0–10.2)
H	3.42 ± 0.19	3.72 ± 0.12	7.0 c ± 4.9		[55]
L	3.37 ± 0.18	3.56 ± 0.10	5.6 c ± 4.6		Glass bead method, helium pycnometry

^a—207 samples from 116 different H chondrites; ^b—79 samples from 63 different H chondrites; ^c—fresh fall.

). Moreover, they also fit the average H chondrite bulk densities determined by Consolmagno et al. [55] (when uncertainties are included) and are close to values for other H chondrite falls obtained by Macke [31]. Despite the fact that grain density is slightly lower than the mean values achieved by either Consolmagno et al. [55] or Macke [31] for H chondrite falls, it still lies within range for them. In fact, the grain density obtained in the current study is closer to the values for finds measured by Macke [31] than for falls. This is also true when comparing porosity (as it is significantly affected by weathering). The other explanation of this fact might be that small samples measured in this work exhibit inhomogeneity of the Pułtusk rock and weathering in terrestrial conditions. Bulk chemical composition data show that the abundances of Fe and Ni in the sample examined in this study were ca. 15% and 20% lower than the typical abundances of these metals in H chondrites (Section 3.1), which can also influence and lower the grain density value.

When comparing Pułtusk with Košice (H5) samples in terms of physical properties, all values determined here are lower than those for Košice [56] (Table 3). It should be noted that specimens of Košice chondrite were measured up to 4 weeks after the fall, so they are significantly less affected by the terrestrial atmosphere and weathering than Pułtusk specimens found 150 years after its fall. Bulk densities measured by the authors of the current study lie within the range for Košice; however, grain density and porosity do not.

Flynn et al. [39] stress, using Holbrook (L/LL6) as an example, where specimens were also collected over a long period of time, that similarities in ρ_g suggest that these differences are not due to different weathering grades, as weathering, which introduces oxides into pore space, alters ρ_g much more than ρ_b. This is probably the reason why the values of ρ_b obtained by the authors are in accord with those determined by Macke [31] or Kohout et al. [56]. However, grain density is strongly affected by meteorite weathering because secondary mineral phases have lower ρ_g than those they replace (e.g., Fe oxides compared to metallic Fe, sulfate compared to sulfide, etc.). Moreover, replacement phases are likely to partially fill void spaces and decrease porosity [57], but these species expand into existing pores without significantly altering the exterior dimensions of the stone, leaving ρ_b unaltered [39]. This explains why the current results for porosity differ significantly from others presented in Table 3, while ρ_b remains similar. Furthermore, pore reduction in the case of ordinary chondrites is a relatively rapid process and ca. 50% reduction in the porosity can occur when a meteorite is turning from W0 to W1 [39]. This is possibly observed in these Pułtusk samples. The other drawback is that while mass and ρ_g can be determined with high precision and accuracy, the measurement of bulk volume is still subject to considerable inaccuracy.

Taking into account that the results for Pułtusk presented in Table 3 come from different specimens of the same meteorite found at different times after its fall (over 150 years), some variability is to be expected, but the data agree reasonably well. The variations can exhibit random heterogeneity between fragments of the same meteorite as well as differences in the measurement technique and weathering grades of particular samples. The classic Archimedean method used in the current study provides a lower-limit estimation of porosity, which in turn affects the grain density value according to Equation (3). Nevertheless, the current data are comparable with others (Table 3), especially in the case of bulk density. To determine thermophysical properties, both the current results and the average for Pułtusk obtained by Macke [31] will be used, since it was measured using more than 20 specimens of this particular chondrite.

A literature study from previous research also shows values of material strength properties of the Pułtusk H5 chondrite that were not measured in the current study. As they are affected by porosity and rock composition it is worth briefly mentioning that the compressive strength of Pułtusk is 213 MPa, its tensile strength 31 MPa [17], and its Young’s Modulus is 76 GPa [39].

3.3. Thermophysical Properties

3.3.1. Specific Heat Capacity

Specific heat capacity determined by DSC in the temperature range between 223 and 773 K (−50–500 °C) increases from 563.7 to 1147.0 J/(kg∙K), and it is equal to 699 J/(kg∙K) at room temperature (300 K). As heat capacity is a temperature-dependent parameter its values are best presented graphically (Figure 4).

A normal exponential function is the best fit for the results for specific heat capacity Cp obtained for Pułtusk. The general equation of this function is then

$$Cp\left(T\right)=\mathrm{A}\mathrm{e}\mathrm{x}\mathrm{p}\left(-\mathrm{C}T\right)+\mathrm{B}$$

(5)

In this study the A, B, and C coefficients are −1386.21, 1330.58, and 0.002657, respectively (root mean square error RMSE = 12.7). This fit is marked in Figure 4 as a black solid line. The same type of expression was used to show Cp(T) dependence for other meteorites, e.g., chondrites: Bursa L6 [58] and Braunschweig L6 [59] or Sariçiçek howardite [60]. Prediction of heat capacity values below or above the Cp measurement range (223–773 K) can be performed using Equation (5). The extrapolated (predicted) values for Pułtusk are, e.g., Cp(175 K) = 460 J/(kg·K), Cp(200 K) = 516 J/(kg·K), and Cp(1000 K) = 1233 J/(kg·K); they are marked in Figure 4 as red circles. Macke [36] reported heat capacity values of two Pułtusk samples at low temperatures, Cp(175 K) = 488.7 ± 3.3 J/(kg·K) and Cp(175 K) = 490.0 ± 0.4 J/(kg·K), which are generally close to the value predicted in this study (Cp(175 K) = 460 J/(kg·K)). Using Macke’s [36] polynomial fit for composition-based model Cp(T) curves for H chondrites over the temperature range 70–300 K, one can calculate heat capacity values at 175 K, 200 K, and 300 K, which are Cp(175 K) = 483 J/(kg·K), Cp(200 K) = 543 J/(kg·K), and Cp(300 K) = 717 J/(kg·K). The Cp data predicted in this study, specifically Cp(175 K) = 460 J/(kg·K) and Cp(200 K) = 516 J/(kg·K) as well as the measured Cp(300 K) = 699 J/(kg·K), are in good agreement with the polynomial fit by Macke [36]. The currently extrapolated value Cp(200 K) = 516 J/(kg·K) is also very close to that measured by Consolmagno [35] at 200 K (Cp(200 K) = 491 ± 10 and 502 ± 25 J/(kg·K)) for Pułtusk.

Moreover, values of Cp from the current study for Pułtusk at 350 K (Cp(350 K) = 779.5 J/(kg·K)) are relatively close to the values obtained for other meteorites belonging to the same group (

Table 4. Comparison of specific heat capacities of different H5 chondrites and H chondrites.

Sample	Petrographic Type	Mass [10−3 kg]	Specific Heat Capacity [J/(kg∙K)]	Temperature [K]	References
Pułtusk	H5	0.023	699	300	Current study
H chondrites	-	-	714		[63]
Y-7301	H4	0.016	364
Y-74647	H4-5	0.0074	601
Y-74371	H5-6	0.0012	535
Pułtusk	H5	0.023	779.5 ± 48.7	350	Current study
Gao–Guenie (07C-TPRL) Gao–Guenie -(08) Jilin	H5	3.01	732.0 ± 7.5		[61]
	H5	61.37	739.7 ± 27.5
	H5	62.35	725.8 ± 13.2

), e.g., Jilin H5 (726 ± 13 J/(kg·K)) and Gao–Guenie H5 (732 ± 7 and 740 ± 27 J/(kg·K)) (data for both meteorites are from Beech [61]). The Cp measured here at 300 K (699 J/(kg·K) fits very well with the average for H chondrites reported by Yomogida and Matsui [62] (714 J/(kg·K)). On the other hand, values of Cp typical for Antarctic finds (named in Table 4, where ‘Y’ stands for Yamato and is followed by numbers) studied by Matsui and Osako [63] are much lower than for Pułtusk, which shows us that weathering of meteorites can significantly lower the values of Cp (as secondary mineral phases have lower Cp values than the primary ones).

When comparing Cp values for Pułtusk with data obtained for Gao–Guenie (H5) [61] it can be observed that Cp values for both meteorites are similar (

Table 5. Comparison of specific heat capacity of Pułtusk (H5) chondrite with other thermophysical properties of Gao–Guenie (H5) meteorite [61].

	Pułtusk (H5)		Gao–Guenie (H5)
Temperature	Heat Capacity Cp		Heat Capacity Cp	Diffusivity D × 10−7	Conductivity K *
(K)	(J/(kg∙K))	SD	(J/(kg∙K))	(m2/s)	(W/(m∙K))
296	699.0	40.5	732.0	12.10	29.92
323	733.4	42.6	773.0	10.90	28.46
373	825.7	54.7	832.0	9.54	26.81
473	927.2	57.2	904.0	7.65	23.36
573	1031.0	75.8	950.0	6.50	20.86
673	1084.9	52.6	976.0	5.89	19.42
773	1147.0	57.1	989.0	5.51	18.41

SD—standard deviation. * The value reported in the paper by Beech et al. [61] is 10 times too high, due to a unit conversion mistake (Beech, personal communication, as stated in [34]).

). At lower temperatures, in the range of 296–373 K the values of specific heat capacity for Pułtusk seem to be lower than those for Gao–Guenie, while above 473 K the reverse situation is observed. However, considering the standard deviation calculated for Pułtusk, these values are in good agreement with the data for Gao–Guenie. It should be noted that Beech and co-workers [61] analyzed samples with larger masses than the authors of this paper (3 g compared to 0.023 g in the current study). Moreover, they measured fresher samples, as Gao–Guenie fell 100 years later than Pułtusk, so the influence of terrestrial conditions was probably much lower. Beech et al. [61] also examined samples cut from the interior of the meteorite to avoid weathering effects and to minimize any effects of surface weathering and/or ablation alteration. Samples used in the current study were prepared from material available for research; analysis of the crust was avoided, and at least a 2 cm distance from the edge of the meteorite was kept.

3.3.2. Volumetric Heat Capacity

Knowing the specific heat capacity from DSC measurement and bulk density from the Archimedean method, it is possible to calculate the volumetric heat capacity (heat capacity per unit volume; Cvol (J/m³K)) of the Pułtusk chondrite using the following equation:

$$Cvol=Cp\times {\rho }_b$$

(6)

where Cp is specific heat capacity and ρ_b is bulk density. Using the experimental data for Cp and ρ_b, Cvol values were determined from Equation (6) as Cvol(300 K) = 2.3 MJ/(m³K) and Cvol(200 K) = 1.7 MJ/(m³K). When taking into account the average bulk density for Pułtusk samples obtained by Macke [31], ρ_b = 3.44 g/cm³, and the heat capacities Cp(200 K) = 543 J/(kg·K) and Cp(300 K) = 717 J/(kg·K) predicted by his model [36], one can obtain the values Cvol(300 K) = 2.46 MJ/(m³K) and Cvol(200 K) = 1.87 MJ/(m³K). We present the results of the calculation of volumetric heat capacity for Macke’s data [31,36] for comparison as that bulk density value can better characterize the Pułtusk chondrite (due to the fact that 23 different specimens of this meteorite were examined). The Cvol determinations for the current data correspond well with those for Macke’s data [31,36] as well as with values characteristic of stony meteorites at room temperature, Cvol(300 K) = 2.5 MJ/(m³K), as shown by Szurgot [64]. Furthermore, Cvol values for current specimens of Pułtusk H5 are very similar to those for the Jezersko H4 chondrite, Cvol(300 K)= 1.8 MJ/(m³K) and Cvol(200 K) = 2.3 MJ/(m³K) [40]. Volumetric heat capacity data for other H chondrites reported by Szurgot [40] also fit well with the current study (

Table 6. Comparison of volumetric heat capacity, atomic heat, and mean atomic weight of different H chondrites.

Thermophysical Properties	Pułtusk H5 (Current Study)	Pułtusk H5 [40]	Jezersko H4 [40]	Jilin H5 [40]	Gao–Guenie H5 [40]	Barbotan H5 [40]
Cvol(MJ/m3K) 200 K	1.7	1.9	1.8	1.9	1.9	1.9
Cvol(MJ/m3K) 300 K	2.3	2.4	2.3	2.5	2.5–2.6	2.6
Catom(J/molK) 200 K	12.1	13.4	13.1	-	-	-
Catom(J/molK) 300 K	16.4	17.1–17.2	17.4	18.4	17.4–18.0	-
Amean(g/mol)	23.39	24.75 *	24.68	-	-	-

*—values from Szurgot [41]; -—not determined in the mentioned study.

).

3.3.3. Mean Atom-Molar Heat Capacity

Mean atom-molar heat capacity Catom(J/molK) is defined as the amount of heat required to raise the temperature of 1 mole of a substance by 1 degree Kelvin. It can be determined at any temperature using the following formula:

$$Catom=Amean\times Cp$$

(7)

where Amean is the mean atomic weight and Cp is the specific heat capacity. The mean atomic weight of Pułtusk was calculated using the bulk chemical composition data for the main elements (Section 3.1), and is equal to Amean = 23.39 g/mol. This value is slightly lower than that estimated by Szurgot [40] for the same meteorite or for Jezersko H4 (Table 6). However, it represents the current sample accurately, as the results of the bulk chemical analysis relate to the same specimen from Pułtusk as the results of the thermophysical measurements. Figure 5 shows the temperature dependence of Catom(T) for Pułtusk, and the best fit for these data can be expressed by the following equation:

$$Catom={\mathrm{A}}^{\prime }\mathrm{e}\mathrm{x}\mathrm{p}\left(-{\mathrm{C}}^{\prime }T\right)+{\mathrm{B}}^{\prime }$$

(8)

where T is absolute temperature (K), and A′, B′, and C′ are constants. For the Pułtusk sample these constants are −31.39, 30.71, and 0.002699, respectively, with a root mean square error RMSE of 0.19. According to Equation (8) the mean atom-molar heat capacities Catom for Pułtusk at 200 K and 300 K are 12.1 J/(molK) and 16.4 J/(molK). These values are similar to although slightly lower than the values for Pułtusk and other H chondrites calculated by Szurgot [40] (Table 6). The main reason for this is the lower Amean value obtained for the sample analyzed in the current study.

3.3.4. Thermal Diffusivity

Soini et al. [54], based on their measurements of thermal diffusivity (D) and thermal conductivity (K), developed the relationship between thermal diffusivity and porosity (D(P)) of chondrite falls for room-temperature (RT = 296–300 K) and low-pressure conditions (pressure values in the range 10⁻⁴–0.1 Pa and also 1 Pa are considered in this paper as a vacuum):

$$D\left(P\right)=-0.0461\times P+0.962$$

(9)

Calculating the thermal diffusivity of the Pułtusk chondrite from Equation (9), the obtained value of D(296 K, vacuum) is 0.81 × 10⁻⁶ m²/s (by substituting the current porosity data for Pułtusk P = 3.22%), and D(296 K, vacuum) = 0.62 × 10⁻⁶ m²/s (when using P = 7.5% from Macke [31]).

Another method to determine D is to use the dependence between thermal diffusivity and bulk density (ρ_b), as presented by Szurgot and Wojtatowicz [65]. It is a linear relationship with the following general equation:

$$D=\mathrm{E}\times {\rho }_b+\mathrm{F}$$

(10)

where the E and F coefficients are constant for a given temperature, e.g., E = 2.49 × 10⁻⁹ m⁵/(kg×s), F = −7.11 × 10⁻⁶ m²/s at 298 K and normal pressure (1 atm); E = 2.11 × 10⁻⁹ m⁵/(kg×s), F = −6.24 × 10⁻⁶ m²/s at 200 K and 1 Pa [65]. Using Equation (10), one can obtain the thermal diffusivity of Pułtusk D(298 K, 1 atm) = 1.10 × 10⁻⁶ m²/s, D(200 K, 1 Pa) = 0.72 × 10⁻⁶ m²/s for the current bulk density data (ρ_b = 3.30 × 10³ kg/m³), and D(298 K, 1 atm) = 1.46 × 10⁻⁶ m²/s, D(200 K, 1 Pa) = 1.02 × 10⁻⁶ m²/s for the ρ_b = 3.44 × 10³ kg/m³ value from Macke [31].

Thermal diffusivity of H chondrites at room temperature and low air pressure (vacuum) is in the range (0.2–1.2) × 10⁻⁶ m²/s [62]. Osako [66] determined D = 0.74 × 10⁻⁶ m²/s for the Kesen H4 chondrite at room temperature in vacuum (1 Pa). Soini et al. [54] reported the thermal diffusivity values for H chondrite finds in the range 0.77–1.35 × 10⁻⁶ m²/s measured at 296 K and 1 atm, and 0.30–1.09 × 10⁻⁶ m²/s for low pressure. All values obtained in the current approach correspond well to the data of other authors mentioned in this paragraph and fit in the presented ranges. Moreover, the current data of D for Pułtusk are very close to the thermal diffusivity values of Gao–Guenie H5 (D = 1.2 × 10⁻⁶ m²/s) [61] (Table 5) and of Cronstad (H5) (1.085 × 10⁻⁶ m²/s) [34], both at 296 K and 1 atm.

3.3.5. Thermal Conductivity

Determination of thermal conductivity values can be performed using different relationships. The first one, shown by Ashby [67], connects thermal conductivity (K) with thermal diffusivity (D) according to the following equation:

$$K=Cp\times {\rho }_b\times D$$

(11)

The presented experimental data of ρ_b = 3.30 × 10³ kg/m³, Cp(300 K) = 699 J/(kg·K), extrapolated Cp(200 K) = 515.8 J/(kg·K), and determined data for D(RT, vacuum) = 0.81 × 10⁻⁶ m²/s, D(RT, 1 atm) = 1.10 × 10⁻⁶ m²/s, D(RT, vacuum) = 0.72 × 10⁻⁶ m²/s let one predict the thermal conductivity values for the Pułtusk chondrite at room temperature to be K(RT, vacuum) = 1.88 W/(m·K) and K(RT, 1 atm) = 2.54 W/(m·K), while at 200 K K(200 K, vacuum) = 1.22 W/(m·K), according to Equation (11). Using data from Macke [31,36], ρ_b = 3.44 × 10³ kg/m³, Cp(300 K) = 714 J/(kg·K), Cp(200 K) = 543 J/(kg·K), and D(RT, vacuum) = 0.62 × 10⁻⁶ m²/s, D(RT, 1 atm) = 1.46 × 10⁻⁶ m²/s, D(200 K, vacuum) = 1.02 × 10⁻⁶ m²/s, we obtained K(RT, vacuum) = 1.52 W/(m·K) and K(RT, 1 atm) = 3.59 W/(m·K), and K(200 K, vacuum) = 1.90 W/(m·K).

Secondly, in order to determine K at room temperature and low pressure, the linear relationship between thermal conductivity (K) and porosity (P) established by Soini et al. [54] for chondrite falls can be used:

$$K\left(P\right)=-0.1457\times P+2.9614$$

(12)

Substituting the current experimental porosity data (P = 3.22%) into Equation (12) gives a thermal conductivity value for Pułtusk K(RT, vacuum) = 2.49 W/(m·K), while using Macke’s data [31,36] (P = 7.5%) K(RT, vacuum) = 1.87 W/(m·K).

A third way to predict K values is by using K(P) nonlinear dependence, developed by Flynn et al. [39] and expressed by the following equation:

$$K=0.11\times {\displaystyle \frac{(1-P)}{P}}$$

(13)

where P is porosity (%). In their paper [39] it is stated that the formula fails for porosity close to 0 but should yield good results for porosity above 2%. However, using the current porosity data for Pułtusk (P = 3.22%), one can obtain K = 3.4 W/(m·K), which is inconsistent with the thermal conductivity data obtained from relationships 11, 12, or 14. On the other hand, substituting Pułtusk porosity from Macke [31] (P = 7.5%) into Equation (13) gives K = 1.47 W/(m·K), which is close to the estimated values for room-temperature and low-pressure K obtained from Equations (11) and (12).

Furthermore, there is a relationship between the thermal conductivity (K) and bulk density (ρ_b) of chondrite falls in low-pressure and room-temperature conditions discovered by Soini et al. [54]:

$$K\left({\rho }_b\right)=4.9287\times {\rho }_b-14.469$$

(14)

For Pułtusk we obtained thermal conductivity values of K(RT, vacuum) = 1.78 W/(m·K) and K(RT, vacuum) = 2.49 W/(m·K) using the present ρ_b data and Macke’s data [31], respectively.

Generally, when comparing all thermal conductivity values calculated for the current experimental data with Equations (11)–(14), it is noted that K(RT, vacuum) calculated with Equations (11) and (14), both showing K(ρ_b) dependency, gives very similar values for the Pułtusk chondrite (1.88 and 1.78 W/(m·K), respectively; average K(RT, vacuum) = 1.83 W/(m·K)). However, the K(P) relationship from Equation (12) gives values of K that are higher (2.49 W/(m·K)) and rather closer to the K value of Pułtusk for the present data and room temperature and vacuum (2.54 W/(m·K)). The value of K determined from Equation (13) is out of the range of K determined by Equations (11), (12), and (14). The reason may be that the determined porosity was affected too much by weathering and/or inaccuracy of the Archimedean method measurement.

When examining K values at room temperature and low pressure (vacuum) for Macke’s data [31,36], both K(P) dependencies (Equations (12) and (13)) yield similar values (1.87 and 1.47 W/(m·K)), which are also comparable with those obtained from the K(ρ_b) relationship (Equation (11)) (1.52 W/(m·K); average K(RT, vacuum) = 1.62 W/(m·K)). Values of K for Macke’s data [31,36] are approximately two times higher at room temperature and in ambient air (1 atm) than those calculated at room temperature and in vacuum.

All thermal conductivity values, obtained from both the present study and Macke’s experimental data [31,36], fall within the K range reported by Soini et al. [54] for H chondrite finds for room temperature and low pressure, as well as for room temperature and ambient air, adequately (0.72–3.09 and 1.83–3.75 W/(m·K), respectively). Opeil et al. [32,34] measured K data at 200 K and low pressure for, e.g., Pułtusk (1.25 W/(m·K)), Cronstad H5 (1.88 W/(m·K)), La Ciénega H6 (1.90 W/(m·K)), and Barbotan H5 (3.05 W/(m·K)). Apparently, these thermal conductivity values vary within the H chondrite group and might reflect individual properties of particular meteorites as they depend both on pores and cracks and on metallic grain distributions in the rock structure. It was also suggested by Soini et al. [54] that thermal conductivity and diffusivity exhibit substantial variation among samples of the same chemical and petrologic type and show considerable overlap between different ordinary chondrite groups. The present K value calculated from Equation (11) for Pułtusk at 200 K and low pressure is identical to that measured by Opeil [32] (1.22 and 1.25 W/(m·K), respectively), while K calculated for these conditions for Macke’s data [31,36] is higher (1.90 W/(m·K), closer to the K value of Cronstad and Ciénega. The K value of the present data for Pułtusk at room temperature and in 1 atm is comparable with that of Gao–Guenie H5 measured by Beech et al. [61] (2.54 and 2.99, respectively).

3.3.6. Thermal Inertia

Thermal inertia of material is a measure of how resistant its surface is to temperature changes, indicating its ability to store and transport heat. The thermal inertia of Pułtusk was determined with the following formula:

$$\Gamma =\sqrt{K\times Cp\times {\rho }_b}$$

(15)

Using both current calculated values of K(RT, vacuum) = 1.83 W/(m·K), K(RT, 1 atm) = 2.54 W/(m·K) and the measured values of Cp(300 K) = 699 J/(kg·K) and ρ_b = 3.30 × 10³ kg/m³, one can get the thermal inertia of Pułtusk Γ(300 K, vacuum) = 2.05 × 10³ J/(s^0.5K·m²), Γ(300 K, air 1 atm) = 2.42 × 10³ J/(s^0.5K·m²). Substituting the current predicted values of K(200 K, vacuum) = 1.22 W/(m·K), Cp(200 K) = 515.8 J/(kg·K) and measured ρb = 3.30 × 10³ kg/m³ into Equation (15) gives the thermal inertia of Pułtusk at low temperature Γ(200 K, vacuum) = 1.44 × 10³ J/(s^0.5K·m²).

Determining the thermal inertia of Pułtusk with Macke’s data [31,36] (K(RT, vacuum) = 1.62 W/(m·K), K(RT, 1 atm) = 3.59 W/(m·K), K(200 K, vacuum) = 1.90 W/(m·K), Cp(300 K) = 714 J/(kg·K), Cp(200 K) = 543 J/(kg·K), ρ_b = 3.44 × 10³ kg/m³) gives the following values: Γ(300 K, vacuum) = 2.00 × 10³ J/(s^0.5K·m²), Γ(300 K, air 1 atm) = 2.98 × 10³ J/(s^0.5K·m²), and Γ(200 K, vacuum) = 1.89 × 10³ J/(s^0.5K·m²).

Values of thermal inertia of the NWA 11038 (L3) and NWA 11344 (L3-4) chondrites at 200 K (2.242 and 2.316 × 10³ J/(s^0.5K·m²)) and 300 K (2.495 and 2.624 × 10³ J/(s^0.5K·m²), respectively) [68] fit relatively well with the current data for Pułtusk. The thermal inertia of Pułtusk corresponds well with the Γ values of Cronstad H5 (1.80 × 10³ J/(s^0.5K·m²)), Gladstone H6 (2.05 × 10³ J/(s^0.5K·m²)), and Bursa L6 (1.84 × 10³ J/(s^0.5K·m²)) at 200 K, in vacuum; with Bursa L6 (2.15 × 10³ J/(s^0.5K·m²)) at 300 K, in vacuum; and with Gao–Guenie H5 (2.72 × 10³ J/(s^0.5K·m²)) and Bursa L6 (2.58 × 10³ J/(s^0.5K·m²)) at 300 K, in air 1 atm (Γ data calculated by Altunayar-Unsalan et al. [58] based on data from [32,34,61,62] and their own data for Bursa [58]). Moreover, all thermal inertia data derived presently for Pułtusk are comparable with data for high-porosity rocks and monolithic rocks [69].

4. Conclusions

The analysis of the bulk chemical composition of the Pułtusk meteorite conducted in this study confirms that the examined specimen is a good representative of the H group of ordinary chondrites. This is also the first published set of complex results (59 elements) of bulk chemical analysis of Pułtusk. The abundance of almost all main elements fits well with the average H chondrite data [48,50]. Only Fe and Ni contents are approximately 15% lower than in a typical H chondrite. As a consequence, both Fe/Si and Ni/Si ratios are almost 20% lower. This fact may reflect (1) a characteristic feature of the Pułtusk meteorite, (2) a generally lower content of metallic grains in the sample used for ICP MS analysis, and/or (3) weathering of the meteorite during the 150 years since its fall. Moreover, this 15–20% lower metal concentration may slightly influence the physical and thermophysical properties of the Pułtusk meteorite. This compositional difference is estimated to reduce its thermal conductivity to a small extent, as discussed in Section 3.1. The elevated abundances of LREEs in the Pułtusk sample relative to average H chondrites suggest a higher phosphate content in the examined specimen.

The currently measured bulk density (ρ_b = 3.30 × 10³ kg/m³) value of Pułtusk corresponds relatively well with ρ_b values reported by other researchers for Pułtusk and other H chondrites. The grain density (ρ_g = 3.41 g/cm³) and porosity (P = 3.22%) obtained here are slightly lower than the mean for H chondrite falls (but still lie within the range for them); it seems that both values are closer to the average for finds than for falls. Specific heat capacity values of Pułtusk measured by DSC (Cp(300 K) = 699 J/(kg·K)) and estimated (Cp(200 K) = 515.8 J/(kg·K)) fit perfectly to the modeled values for low temperature.

The determination of bulk density, grain density, porosity, and specific heat capacity and the knowledge of the chemical composition of Pułtusk allowed us to derive other properties of this meteorite for different temperature and pressure conditions:

-

Volumetric heat capacity Cvol(300 K) = 2.3 MJ/(m³K) and Cvol(200 K) = 1.7 MJ/(m³K);

-

Mean atomic weight Amean = 23.39 g/mol;

-

Mean molar atomic heat capacity Catom(200 K) = 12.1 J/(molK) and Catom(300 K) = 16.4 J/(molK);

-

Thermal diffusivity D(296 K, vacuum) = 0.81 × 10⁻⁶ m²/s, D(298 K, 1 atm) = 1.10 × 10⁻⁶ m²/s, D(200 K, 1 Pa) = 0.72 × 10⁻⁶ m²/s;

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Thermal conductivity K(RT, vacuum) = 1.83 W/(m·K), K(RT, 1 atm) = 2.54 W/(m·K), K(200 K, vacuum) = 1.22 W/(m·K);

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Thermal inertia Γ(300 K, vacuum) = 2.05 × 10³ J/(s^0.5K·m²), Γ(300 K, air 1 atm) = 2.42 × 10³ J/(s^0.5K·m²), Γ(200 K, vacuum) = 1.44 × 10³ J/(s^0.5K·m²).

Previous studies reported thermophysical properties of Pułtusk in a very limited range of up to 350 K, whereas this study extends it up to 773 K. The data presented here, both measured and derived, can serve for modeling the physical and thermophysical properties of H chondrites and their parent bodies, although the weathering effect of the Pułtusk sample also needs to be considered. The heat capacity values measured in the current study for the first time for Pułtusk over a broad temperature range and the determined densities, diffusivity, and conductivity can be directly used for an atmospheric entry model of meteoroids (requiring thermophysical property values in the temperature range of 300–1400 K [21]). The low-temperature values of extrapolated heat capacity, conductivity, and density are needed to model planetary/asteroid surface and subsurface temperatures [70]. Moreover, the porosity, conductivity, heat capacity, and density values can serve for modeling of the thermal history of H chondrite parent bodies [25,26]. These are just three examples of further uses of the data presented in this report.

In summary, the integration of the physical and thermophysical properties determined in this study with comprehensive chemical composition represents an achievement not realized by earlier researchers, primarily due to their limited access to sample materials and advanced measurement instruments. The agreement between the present results and those reported by other investigators serves as validation of their novel experimental techniques employed in this field, such as the modified Archimedean method using glass beads, helium pycnometry, and 3D laser scanning which, to the best of our knowledge, have not been performed before.